The invention discloses a solving method for a six-degree-of-freedom series robot inverse kinematics solution. The method comprises the steps that connecting rod parameters are read in and a robot connecting rod coordinate system model is established; the joint positions of the tail ends of connecting rods are known, and joint position constrained equations are established; all the joint positions are determined according to all the joint position constrained equations; the attitude constraint equations of all joint coordinate systems of a robot are established; the solutions of the joint position coordinates obtained before are substituted in the attitude constraint equations respectively, and each group of joint variable intermediate values are solved according to the attitude constraint equations; and the joint variable intermediate values are analyzed, and an optimal joint variable solution is selected. The positions and the attitudes in the robot inverse kinematics solution are separately solved by adopting the spatial geometry theory so that complexity of geometric inverse kinematics solution operation can be greatly reduced, and the method can be applied to the field of robot space obstacle avoidance.