Abstract: The lifting upender is the key equipment of the shearer in the head end of the spent fuel reprocessing. In order to realize the function of lifting the turning action synchronously, a new lifting upender based on double guide rail with lifting flip synchronous mechanism was designed, and safety anti falling unit was set in the structure to ensure the safety of spent fuel assembly in emergency. In order to further ensure the structural safety of the spent fuel assembly under the normal conditions of lifting and lowering and the abnormal conditions of wire rope fracture, the dynamic simulation analysis was carried out with designed equipment as the research object. The movement law of key components of the multi-body mechanical system and the complex force characteristics in operation were analyzed. The speed and acceleration characteristic curves of the whole operation process of the equipment under different working conditions were obtained by using ADAMS software. The results show that the impact force of the spent fuel assembly is less than 10 kN, and the velocity fluctuation of the turnover bin is less than 10% in the process of the double guide rail with lifting flip synchronous mechanism. The simulation results verify the rationality of the system design.