Aiming at the problems of low stiffness and poor machining accuracy of industrial robots in automatic drilling and riveting of large-scale components such as aerospace aircraft skin panels,taking KUKA KR600 R2830 industrial robot as an example,the stiffness was optimized by adjusting the machining posture of industrial robots.The kinematics model of the selected industrial robot was established,then the stiffness model was established and the joint stiffness of the industrial robot was solved through the stiffness identification experiment.Monte Carlo method was used to draw the workspace of industrial robots and stiffness cloud map was drawn based on the workspace with the stiffness performance evaluation index.Combined with the simulated annealing algorithm after parameter optimization,the stiffness optimal posture of the manipulator and the joint angle under the current posture were solved.Finally,simulation and experiment were used to verify the effectiveness of the maximum stiffness pose.This method can provide ideas and guidance for the research of machining stability of high-precision and heavy-duty industrial robots,and improve the drilling and riveting quality of 6R industrial robots.