Only the Fifth Army, the Eighth Army, the Fourteenth Army, the Fifteenth Army, the Sixteenth Army, and the rest of the Fifth Army were brought back to Longcheng by tens of thousands of soldiers who fell under the hands of Wei Wushu, the elite of Wei State. Now there are 200,000 troops in the 200,000 Army of the 20th Army in Longcheng, and only the Fifth Army and the newly recruited Fifth Army remain. King Yingzheng of Qin knew that Long Hui had suffered a lot of losses, so he allocated 50,000 soldiers to Long Hui, and Long Hui recruited another 50,000 troops to gather the 20 armies. Long Hui asked Pang Juan to lead the recruits in training. The remaining 100,000 Long Hui led the war to attack the Qi Kingdom. Since the Battle of Jixi was heavily damaged by the Yan army, the strength of the Qi State has not been able to recover. Under the policy of distant friendship and close attack, the Qin State adopted all non-military means to strive for the neutrality of the Qi State, so as to weaken the strength of the Six Kingdoms to resist Qin. For the sake of his own immediate interests, Qi Jun also adopted a good policy towards Qin, and did not dare to support the other five countries to resist Qin. Because of Qi Wangjian's "Qin Jin". After the victory of Qi Cheng, he bought a lot of money for Qin, and only fantasized about an alliance with Qin, neither cooperating with other countries to resist Qin, nor strengthening war preparedness in his own country. The King of Qi completely listened to Hou Sheng's proposition. It was not until after Qin had conquered the Five Kingdoms that the King of Qi sensed the threat of Qin and hurriedly gathered his army to the west to prepare to resist the Qin army's attack. On the grounds that Qi refused to allow Qin's envoys to visit Qi, the king of Qin avoided the main force in the western part of Qi, and ordered Wang Ben to lead the Qin army from the south of the former Yan State to attack the Qi capital Linzi. The morale of the Qi army was not strong, and it was even more unprepared for the sudden attack of the Qin army from the north. Quickly fell apart. The Qin army captured Linzi in one fell swoop, captured Qi Wang Jian, and died in Qi. The king of Qin set up Qi County and Langxi County in Qi.

After Qin destroyed the Six Kingdoms and initially unified the whole country, because during the Unification War, all countries had no time to take care of the Xiongnu in the northern frontier, resulting in the rapid development of the Xiongnu during this period. In the early days of the unification of the country, the Xiongnu had driven the east from Hu to the east of Yanshan, and the west from Yueshi to the west of the Qilian Mountains, and the main force of the Xiongnu seemed to be in the west of the Yinshan area and the north of the Helan Mountain area, and one of them had invaded the border area of the Hetao area to the Qinyuan Great Wall, forming a great threat to the Guanzhong region. Qin Shi Huang ordered Meng Tian to conquer the Xiongnu in the north. Meng Tian's operational objectives are as follows:

Break the Xiongnu army that invaded the Hetao area of Longxi and the border of the former Zhao State, and expel them to the west of the Helan Mountains and the Langshan Mountain Range, as well as to the north of the Great Wall built by the former Zhao State.

Meng Tian decided to enter the northern part of the Hetao with the main army from Shangjun, and with a part of the army, he left Xiaoguan from Beidi County and entered the southern part of the Hetao, so as to sweep away the Xiongnu army in the Hetao area. After clearing the enemy in the Hetao area, the main army crossed the Yellow River from the northwest of the Hetao and attacked the Gaoque and Langshan mountain ranges. The other crossed the Yellow River from the southwest of the Hetao and captured the highlands of the Helan Mountains to flank the main army.

Meng Tian set out from Shangjun and entered the northern part of the Hetao through Yulin, and an army entered the southern part of the Hetao from the road of Yiqu Xiaoguan. By the early winter of this year, all the Xiongnu tribes in the Hetao area had been swept away, and the remnants of the Xiongnu fled across the river to the northwest. Meng Tiannai pushed the two armies to the south bank of the Yellow River and spent the winter in anticipation of the next spring's fighting.

Meng Tian's main army crossed the Yellow River from Jiuyuan and attacked Gaoque and Taoshan, and a part of the army crossed the Yellow River west into the Helan Mountains. The Xiongnu were shocked by the might of Qin's troops and fled to the north. As a result, all the places occupied by the Xiongnu in Qin and Zhao were restored.

After the war, Meng Tian was ordered to build the Northwest Frontier Great Wall, which was stationed in Jieshang County. When Meng Tian was alive, the Xiongnu did not dare to go south.

Qin Shi Huang divided Longcheng into Longcheng County, and Longhui was stationed here.

Qin Wangzheng was not enough to show his profession, but he was called the emperor and was Qin Shi Huang. And continue to implement the Legalist policy of Shang Yang since the reform of filial piety, strengthen the absolute monarchy, weaken the power of the old aristocracy, and promote the nobles who have risen from military merits. The land ownership system of the Qin Empire basically maintained the "king-owned" land system of the Western Zhou Dynasty, and changed "king-owned" to "state-owned". Qin Shi Huang ordered the peasants of the whole country to report the actual amount of land they possessed in order to collect taxes. It is also practiced that even civilians can be granted land and titles as long as they have military merits. Although the Qin State implemented the "land grant system" during the Shang Dynasty reform, and the peasants' land was nominally owned by the state and privately cultivated, this move allowed the people of the whole country to actually occupy the land that was originally "owned by the king", and soon evolved into a situation where farmers and officials could buy and sell land freely, so the Qin Dynasty's Shang Dynasty Reform eventually facilitated the development of private land.

After Qin Shi Huang abolished the feudal system, he established a set of county and county systems and bureaucratic systems from the central to the local level. At first, the country was divided into 36 counties, and later increased to 46 counties with the expansion of land, and Xianyang was designated as the capital. The highest bureaucrats in the central government are the Prime Minister, the Imperial Historian, and the Taiwei, also known as the "Three Princes". The magistrate of the local county shall be the guard, and the magistrate of the county shall be the order. The county system initially broke the patriarchal system of blood relations, and the feudal system and bureaucracy replaced the hereditary system of the aristocracy. In order to consolidate his power, Qin Shi Huang also implemented a series of policies, mainly: the unification of currency and weights and measures; Unified text; the construction of the Great Wall, galloping roads and straight roads; Forced relocation of rich people and civilians from the six countries. After Qin unified the Six Kingdoms, in order to prevent the nobles of the Six Kingdoms from "resurrecting" by relying on their clans, they were forced to move to Xianyang, asking them to take care of the imperial tombs, or to migrate to the remote areas of the southwest. The Qin general Meng Tian seized Jiuyuan Henan, set up 34 counties, and established Jiuyuan County.

Before Qin Shi Huang became emperor, there were many Legalists who entered Qin from Jin and other eastern countries. The First Emperor once issued the famous "Expulsion Order" to expel the scholars of the Six Kingdoms in the Qin State. Because of Li Si's letter of advice, the first emperor stopped this order.

After the unification of the Six Kingdoms, all kinds of schools and talents who were strongly opposed to the Shang Dynasty during the Shang Dynasty Reform came to Qin State to serve, and it may be that Qin Shi Huang adopted the "Shang Dynasty Reform Law with Qin State Characteristics", which caused various superstitions to prevail in the Qin Empire. Among them, Huang Lao Taoism, Yin and Yang, they synthesized the doctrines of Confucianism, law and Taoism, and put forward the so-called "Five Virtues and Beginning Theory", especially won the trust of the first emperor, the first emperor then thought that Qin is the virtue of water, Zhou is the virtue of fire, and water can overcome fire, so Qin has the world. The Confucian scholars from Qi Yan also made a makeover and modified the Confucian "Feng Chan", and it is rumored that the emperors from ancient times did not hold a ceremony to seal the Zen.