The foot force and joint torque of quadruped wall climbing robot are important bases for the design of robot adsorption structure and the selection of joint motor.Considering the change of gravity and adsorption posture, the finite element analysis of foot force and joint torque requires repeated grid meshing and simulation analysis, which requires a lot of work.A simple and unified semianalytical solution combining kinematics, statics and finite element analysis was proposed to solve the foot force and joint torque of quadruped wall climbing robot with different adsorption posture.In the example, 84 groups of data were obtained by the semi analytical method, and the variation laws of the foot force and joint torque under different posture were analyzed.Based on the results of the example, the adsorption force design of the robot and the selection of the joint motor were completed.Finally, the maximum joint torque of the robot under different postures was measured experimentally.The experimental results show that the adsorption force design of the robot and the selection of the joint are reasonable, and the error of the maximum joint torque calculated by the semi analytical method is less than 8.86%.