Abstract: Master arm is a key device for master slave manipulation system (MSMs), It is n ot only to measure the human operator’s arm motion, but also to telepresence the forces the slave arm will receive from the environment during tasks, and is an important man-machine interface for establishing a kinesthetic coupling between operator and telerobot. thus, its performance will directly affect the maneuve rability of MSMs. So far, a variety of master arm designs have been developed for teleoperation, but the evaluation method and evaluation index of master arm have seldom been studied. The unclearness of aim will bring about the blindness of design. In this paper, we attempt to explore it based on our experience of development in master arm and offer the evaluation method and eval uation index of master arm.