An online calibration method of a six-axis force sensor for the industrial robot was proposed based on the requirement of realtime detecting of end effector working force of industrial robots. First, establish a calculation model of a sensor data relationship, and on this basis, focus on the interference caused by the sensor’s “zero drift”. Then, the least square method was used to identify the base angle,end effector weight and barycenter coordinate parameters of the robot. Finally, according to the real-time kinematic parameters of the robot, the time series method was utilized to compensate for the weight of the end effector and the zero of the sensor online. Experiments show that the online calibration method can eliminate the interference caused by the “zero drift” of the sensor compared with the static calibration method, and have a better online compensation effect. Through real-time tracking detection of the external constant and variable forces received by the end-effector of the industrial robot, the validity and practicability of the algorithm are verified.