Although Meng Ming was overwhelmed by Yelu Yanni, he was still entangled in official duties and could not be idle. This is not today, Meng Ming was summoned to the court, that is, to participate in the negotiation of the imperial court reform of the currency system.

With the increasing prosperity of the Great Song economy, there were more and more large-scale and huge transactions, and they became more and more frequent. At this time, the Great Song Dynasty mainly used copper money to settle, some state roads use iron money, such as Yizhou Road (now Sichuan) uses iron money, it weighs small, consistent money, 1000 big money weighs 25 pounds, and it takes 90 pounds to hundreds of pounds of copper money to buy 1 piece of silk, so it is very inconvenient to circulate. At this time, paper "Jiaozi" has appeared in Sichuan, replacing copper coins in circulation. 30 copper coins must be deducted for each coin.

At this time, the "Jiaozi" is just a deposit certificate. With the development of the commodity economy, the use of Jiaozi is more and more extensive, Jiaozi shop is widely distributed, and take it at any time, abide by the credit, the reputation is very high, in order to avoid the inconvenience of metal currency handling during the transaction, the cases of directly using Jiaozi to pay for the goods are increasing, so it has some functions of currency in long-term circulation, and has become a real banknote. However, it is only a private "personal relationship" and is not recognized by the government. However, not all Jiaozi shops can operate in accordance with the law, "after the rich people declined slightly, they could not repay their burdens, and there were several lawsuits," with the gradual expansion of Jiaozi's influence, the need for standardized management has become increasingly prominent. From 1004 to 1007, Zhang Yong, the governor of Yizhou, rectified the Jiaozi shop, eliminated the lawbreakers, and operated it exclusively by 16 wealthy merchants, so that the issuance of "Jiaozi" was officially recognized by the government. In addition, the government saw that it was profitable to issue Jiaozi, and in the first year of Tiansheng (1023), the local government of Yizhou set up Yizhou Jiaozi, with a capital of 360,000 yuan as a reserve, and the first issuance of "official Jiaozi" was 1.26 million yuan, with a reserve rate of 28%. At this time, Jiaozi is a local currency.

Although it is said that the economic prosperity of the Great Song Dynasty is the most in all dynasties, there is no one who can control it. But at this time, the means of transportation were extremely rudimentary, and merchants who traveled long distances to do business. Heavy iron money is not conducive to long-distance commodity trading. It is the need of each currency area to prevent the outflow of copper coins. The Northern Song Dynasty was highly centralized politically, but economically it was not monolithic, the national currency was not unified, and the currencies of various currency ranges were not common to each other. At that time, there were thirteen roads in the country (the highest level of local division in the Song Dynasty, roughly equivalent to the Tao of the Tang Dynasty, the state of the Han Dynasty, the fifteenth road in the time of Taizong, and the eighteenth road in the time of Renzong) special copper coins and six roads dedicated to iron coins. Currency outflow is strictly prohibited in each currency area, so the currency system is chaotic and not conducive to circulation. The imperial court decided to unify the currency system, take back the coinage rights in various places, and set up a numismatic bureau by the imperial court to issue currency in a unified manner, referring to the successful experience of Jiaozi.

Meng Ming also wrote a pamphlet "Discussion on the Issuance of Money in the Great Song Dynasty" with reference to the currency issuance system of later generations, proposing that the currency system of the imperial court consisted of metal coins and paper coins, which were issued and used by the state for compulsory use. Paper money represents metal money and performs the functions of a means of circulation and payment (mainly limited to domestic use). In particular, the issuance of paper money is particularly critical, paper money first evolved from metal money, without metal money, there is no paper money; secondly, paper money performs the function of a means of circulation only according to the value of the metal money it replaces; Finally, the amount of banknotes issued must be limited to the amount of money actually needed in circulation.

In particular, Meng Ming proposed the principle of paper money issuance, proposing the copper standard and the gold and silver standard, with each unit of currency worth equal to a certain weight of gold (i.e., the gold content of the currency); The base currency can be minted freely. Under the paper money system, the standard currency is issued by the state monopoly. The base currency has unlimited solvency. and the relevant exchange ratio, that is, how many banknotes are exchanged for one tael of gold and silver, and the banknotes issued must be linked to gold, silver and copper. In particular, it is not allowed to issue paper money indiscriminately, causing currency depreciation, causing inflation, and affecting the country's credit system.

Meng Ming divided the denominations of coins into six types: one wen, five wen, ten wen, twenty wen, fifty wen, and one hundred wen; There are eight denominations of banknotes: 1 yuan, 5 yuan, 10 yuan, 20 yuan, 50 yuan, 100 yuan, 500 yuan, and 1,000 yuan. The exchange ratio is that one yuan is equal to one hundred yuan, and it is always equal to ten yuan, which can be exchanged with the same amount of silver and gold, one tael of gold is worth one hundred yuan for ten taels of silver, and one tael of silver is equal to ten yuan for the consistent value, and so on. Later, six types of banknotes were issued, which were divided into 1 wen, 5 wen, 10 wen, 20 wen, 50 wen, and 100 wen.

He also put forward the bank's plan "Banking Theory", proposing the establishment of the Great Song Dynasty Royal Bank and the establishment of branches in the grassroots counties to exchange money, keep money, receive and pay cash, handle settlement and remittance, and collect custody fees and handling fees; When the time is ripe, it can carry out the business of absorbing customer deposits and issuing loans, pay interest on deposits, and collect loan interest. It also proposes a reserve system for each branch to ensure the payment and liquidation of the bank. It has also formulated a system of supervision and control for banks, especially the financial system and the auditing system. Contingency plans for related emergencies have also been formulated, such as dealing with emergencies such as runs.

Meng Ming also proposed a bill to allow the establishment of private banks, and asked the imperial court to establish a banking regulator: the Banking Supervision Bureau.

Meng Ming's plan was also placed in the court, and the officials and important ministers referred to it. Because Meng Ming's "Proposal on the Issuance of Money in the Great Song Dynasty" and "On Banking" were brand-new affairs and concepts, it took time for everyone in the court to digest and absorb them, and the court needed to deal with them carefully. However, the money production can be tried immediately, and Meng Ming is in charge; At the same time, Meng Ming's application for the establishment of the Da Song Commercial Bank was approved.