Aimed at the contradiction between the function transit and safety of functional prosthesis，a timeshared load-bearing interface with shape variable socket for functional prosthesis was proposed, which can solve the problems resulted from longtime overload, such as ischemic tissue necrosis. Compression cavity units with negative stiffness were designed to clamp the soft tissue of the body by making the cavity unit to contract. Negative stiffness of variable cavity unit makes it easier to adjust the tightness of soft tissue compression and provides the socket with the function of overload protection. The experiment has proved that the design is feasible.