Due to its flexibility and safety, soft actuator has been widely used in robot assisted rehabilitation. However, the traditional actuator cavity structure has the problems of excessive expansion, single bending form and stress concentration, which affects the repeated rehabilitation training. In this paper, a fiber reinforced pneumatic soft actuator structure based on asymmetric chamber is designed, which includes silica gel matrix of asymmetric chamber, radial fiber reinforced structure and bending restraint layer. The influence of actuator structural parameters on bending performance is studied by finite element simulation. Finally, the pneumatic control system is built to test the performance of the software actuator. Through the bending angle test and end contact force test, the grasping ability of the designed actuator is verified, which can meet the daily rehabilitation needs.