Abstract: For the series structure characteristics of industrial robots, the stiffness of industrial robots is lower than CNC machine tools, which will cause poor processing accuracy and processing quality of the robots. In order to improve the stiffness of industrial robots, a method for solving the processing posture of the robot was proposed based on the inverse kinematics of the robot. This paper takes the IRB6700 robot as the research object. Firstly, the optimal inverse posture configuration of the robot can be obtained by comparing the processing stiffness corresponding to the different inverse postures of the robot. Furthermore, considering the redundancy of robot processing, the inverse attitude of the robot is solved, the robot posture optimization model is established, and the optimization results under the given processing condition are obtained. Finally, finite element simulation is used to verify the correctness of the optimization of grinding posture based on inverse kinematics of robot.