Abstract: A synovial variable structure and Lyapunov power distribution stability control strategy of hybrid energy storage system (HESS) in hybrid electric vehicles (HEV) is presented. The strategy aims to control power converters based on the synovial variable structure in order to satisfy the following requirements:stabilized dc bus voltage regulations and perfectly tracked of SC current to its reference. At the same time, the stability of the closed-loop control system based on the Lyapunov theory is analyzed. The HESS and control strategy are modeled and simulated under the ADVISOR simulation environment, and a prototype of HESS is also built. The results show that the designed control strategy meets all the objectives and achieves asymptotic stability of the closed loop system.