Rehabilitation system for upper limbs is the device of implementing rehabilitation for patients' wounded limbs instead of therapists. According to review the development of rehabilitation system, we find some deficiencies such as insufficient movement space, few exact evaluations for impairment, and inadequate support for serious hemiplegia. Aiming at these problems, a novel rehabilitation system for upper limbs based on sEMG (surface electromyographic) signal is developed. The proposed system imitates human arm movements and can implement space motion because of its 5 DOF. As a diagnostic tool, the system is introduced sEMG, which is considered as the main basis of evaluation for motor function impairment. Software is developed to analyze sEMG signal during the movements to obtain valid characteristic parameters with time-, frequency-, and time-frequency-domain analytical methods. These parameters are associated with those of other sensor signals such as joint torque, joint angle, and force to quantify motor function injury. As a therapeutic tool, it can provide effective plans based on the parameters mentioned above. During the course of exercises, changes of each sensor signal and their characteristic parameters can be detected and monitored on the intuitive software interface, which can guide the device to carry out trainings. It provides a good platform for researching of sEMG signal and provides a new path for clinic hemiplegia upper limb therapy.