Abstract: Taking redundant actuated manipulator with planar 3 degree of freedom as subject investigated, the kinematics model was deduced. Based on the virtual work principle and the equivalent force theory, the dynamic model was built. After the fault tolerant performance of redundant actuated manipulator was discussed, the force abrupt change of driving joint before and after fault occurrence was defined. Furthermore, the uncertainty of redundant actuated manipulator dynamics inverse solution was analyzed. To improve the reliability and fault tolerant performance, a new force allocation approach was brought forward. By taking the reliability of actuator as coefficient multiplier, the uncertain solution was constructed from the certain force allocation solution after failure. The sums of force abrupt change got calculated with traditional approach and this new method were compared. Data simulating result indicates this approach has an outstanding fault tolerant performance.