This paper analyzes the functional requirements of the electric diaphragm spring clutch actuator in thefixed shaft transmission for hybrid vehicles.Then,a design to apply a two- way overreach clutch to the clutchactuator is proposed,which is used to realize positive high efficiency driving and the reverse self- locking function atthe same time.Moreover,the authors describe both the working principle of the proposed clutch actuator and themechanical structure of its prototype,and analyze the principles in great detail of how the two- way overreach clutchrealizes the reverse self- locking and the positive high efficiency driving function.Finally,the feasibility of theproposed clutch actuator is verified by experiments,and its shortcomings and corresponding solutions are alsoexpounded.