Abstract: In this paper, a novel approach to inverse kinematics solution for a 9-DOF modular reconfigurable robot produced by German AMTEC corp. is proposed. Screw theory is applied in this paper. The robot can be divided three parts and every part was uncoupled each other. By adding three constraints on the robot system, all joints′ displacements can be acquired at the certain end-effector′s position. Because the modular robots can be assembled at any type of robot system in theory, this approach to inverse kinematics solution is significant for other robot system.