Abstract: The optimal nonholonomic motion planning for free-floating space robot system with dual-arms is discussed. Based on the linear and angular momentum conservations of the system, the system state equations for control design are established, so the nonholonomic motion planning objective of attitude control for space robot system is transformed as the solution of a canonical nonlinear control problem. The optimal control scheme for the proposed system is studied, and a numerical algorithm for computing approximate optimal control of the system is developed. The optimal motion planning approach proposed above possesses the advantages of obtaining the desired angles of the base＇s attitude and arms＇ joints only by controlling the arms＇ joints motion. A planar free-floating space robot system with dual-arms is simulated to verify the proposed approach.