Abstract: Structure of agricultural threshing mechanisms is complex, and working conditions are harsh, making it time-consuming and laborious to conduct physical research．The use of digital twin system can monitor working status of threshing mechanism in real time, predict faults, accumulate data, and provide solutions．Research on digital twin system of threshing mechanisms indicated that, drum torque, drum speed, earing temperature, vibration acceleration and power consumption were selected as key parameters to accurately judge physical entity of threshing mechanism．The use of Unity software and AMESim software to construct a digital twin system of physical entity could be used for virtual simulation．The use of ZigBee wireless communication for data exchange could meet needs of digital twin data exchange．