Abstract: Accompanied by the establishment and long-term use of " Kaiyuan Tongbao” (" 开元通宝”) copper coins credit, the system of coexistence of using copper money and silk has been gradually established. The status of copper coins in economic activities has been increasing, and a large number of cases in which the stolen property is recorded in the amount of copper coins can often be seen in historical records, thus forming a dual writing mode of " calculating stolen property by copper coins” and " calculating stolen property by silk” in the field of " responsibility for the corrupting affairs”. Copper coins has gradually gained an economic position that can be against with silk, which even becomes the direct basis for calculating stolen property in the Dahe and Huichang period. However, because the Tang governmen always adhere to the established strategy of " textiles are the fundamental and copper money is the incidental”, copper money cannot completely break through the existing pattern and replace the status of silk, becoming the basic basis for calculating stolen property. The application of the sentencing principle, " calculate copper coins according to the amount of stolen property, and then convert into silk according to the legal provisions”, is exactly the realistic reflection of the dual currency pattern in the judicial field of Tang Dynasty.