Tea merchants are all guided by law. The central household department will introduce tea to tea-producing counties for sale. Where merchants buy tea, they will go to the official newspaper, sell it in the place where they sell tea, pay for it, and buy tea from tea merchants and sell it abroad. Every 100 Jin of tea, one less is called abnormal zero, and another tea is issued, allowing 60 Jin of tea. According to the distance of the tea planting area, the official will set a time limit. After approval, check as usual, cut off the leads and corners, and no other entrainment is allowed. Tea and quotation will go hand in hand. If there is no tea, it will be carried in excess, and it will be punished as private tea, and many people will be arrested. Tea garden households sell tea to merchants without reason, and it is not official to chase the original price. Merchants who transport tea to the place of sale must pay one-thirtieth of the business tax to the tax authorities. After buying tea, submit the original quotation to the local county lawsuit and send it to the original batch inspection office and remittance office for cancellation. If the quotation is not submitted within the time limit, the batch inspection office will find out the address of the merchant every quarter, and according to the questions raised by the inspection department, transfer the quotation and the quotation quantity to the local inspection office for recovery and submit them to the department for cancellation. For commercial tea in Sichuan, the government also divides tea introduction into edge introduction and belly introduction according to the different sales targets and scope, as well as the quality, production methods and traditional supply and marketing relationship of tea. In Ganzi, Aba, Guoluo, Qinghai, Tibet and other Tibetan areas, the border introduction marketing was carried out, and the abdomen introduction marketing was carried out in the mainland, forming a "two sides and one abdomen" system for introducing Sichuan tea to the shore.
Changing official tea for horse is the focus of tea law in Ming Dynasty. "The state attaches great importance to horse politics, so the tea laws are strict", and Tea and Horse Department was set up to take charge. The government has successively set up tea and horse departments in Qin Zhou (later moved to Xining), Hezhou (now Linxia, Gansu), Zhou Tao (now Lintan, Gansu), Zhuanglang (now Shuideng, Gansu), Zhou Min (now Minxian, Gansu), Yongning (now Xuyong, Sichuan) and Diaomen, Yazhou (now tianquan county, Sichuan), mainly in Xining, Hezhou, Zhou Tao and Diaomen. The government takes strict precautions against tea smuggling in northwest and southwest minority areas, and regularly sends officials to check the customs to catch private tea. Private tea exits and customs oversight should be severely punished. In the thirty years of Hongwu (1397), a LUN Ouyang surnamed Xu transported private tea from Shaanxi to Hezhou, was sentenced to death, and the tea goods were confiscated. It was not until the Sejong period of the Ming Dynasty that the crime of private tea was reduced and ended in banishment.