Aiming at the problems of complex process and the unclear geometric meaning in solving the inverse kinematics of 6-DOF serial robot,a solving method based on combined geometric method and screw theory method is proposed. The kinematics model of the robot is established based on screw theory,and Paden-Kahan sub-problem method is often used to solve the inverse kinematics problem. However,for the robot whose first three axes are not intersecting at one point,it is difficult to apply the existing sub-problem to solve.Therefore,a geometric method is used to solve the value of the first three joint angles,and for the robot with the last three joint axes intersecting at one point,by using the Paden-Kahan sub-problem method,a closed-form solution of the inverse kinematics of the robot is derived. The effectiveness of the algorithm is verified by ABB1410 robot.