The hydraulic lifter is mainly used in automobile testing and repairing. At present , most of hydraulic lifter adopts two cylinders structure, and the synchronization of two cylinders is realized by the connection of steel wire and chain. The problem of this lifter is under most circumstances only one cylinder is working, and another cylinder is moving positively by the pull of steel wire. To solve this problem, through adopting an unique three-gear structure which can guarantee the flow capacity to each cylinder is very even, this paper develops a good property, low cost, simple structure and easy installing synchronizer of hydraulic lifter. The hydraulic lifter installing this synchronizer can delete the original steel wire and chain. The experiment shows that the error of output flow capacity to each cylinder is very small and synchronizing precision is very high.