A new design method for service robot arm configuration was proposed. The form of the human arm movement was studied, and the profiling was done. Then mathematical model was established, and dynamic analysis was done with Newton-Euler method, thereby the motor and reducer were selected. The specific designing of manipulator was done with three-dimensional (3-D) modeling techniques of UG, including using UG to do robotic mechanism designing and to optimize robot arm structure. Simulation and analysis were conducted with ADAMS and ANSYS. The results indicate that the manipulator designed is ensured of being lightweight, and is able to meet the requirements of strength and stiffness at the same time.