The compact integrated joint with embedded torque sensor can increase the load-to-mass ratio of the robot, improve the safety of force control, and is more suitable for the service industry. By studying the joint of the light cooperative robot, the overall design scheme of the joint system of the robot is presented. Based on the joint design parameters, the reliability of the joint system under load was studied. Based on the analysis of joint torque characteristics, 17 types of joint torque sensor body are designed. The finite element simulation method is adopted to verify the rationality of strain gauge installation position. The amplifying and low-pass filtering circuit system is developed, and the sensor is calibrated by experimental analysis, the load voltage characteristic curve is fitted, and the linearity, hysteresis, zero drift and sensitivity parameters are obtained. Finally, the load test of the whole joint system is carried out and applied to the 5-DOF carbon fiber robot manipulator system. The results show that the robot joint has high light load and high precision and sensitivity.