Abstract:Due to the current situation that the torque wrench must be set the allowable torque value manually, designed a displacement allowable torque sensor to calculate the allowable torque value through the automatic identification bolt specifications. The size of opening adjusting of bolt clamping device and the potentiometer resistance were associated by gear for identifying bolt specifications. SCM HT66F50 collected potentiometer analog signal by the analog-digital conversion and processing operation by the liquid crystal display module LCD1602 display data. By fitting the data and derivation established allowable torque calculate theoretical, Using the proven hardware integration module, software design is modular thinking, improved the maintainability and reliability of the system. After experimental test prototype, it has meeted the design requirements.