Abstract: In order to solve the problem that the communication interface of digital torque wrench required small volume and low power consumption, a USB serial communication circuit based on CH341T was designed. The principal computer software was developed in VB environment with STC12LE5410AD SCM as slave computer to measure the torque, and the data transmission between digital torque wrench and PC computer was realized. Experiments showed that the communication interface circuit was simple and reliable, it was especially suitable for portable devices.