Recently, the power system equipped in elevator contains motor and gear reducer to get large output torque. The purpose of this paper is to propose a desgin methodology for the kinematic design and efficiency analysis of planetary gear reducer for elevator. First, according to the concept of train value equation of the train circuit, the 2 stage planetary gear reducer is synthesized. Then, according to the latent power theorem, the mechanical efficiency of 2 stage planetary gear reducer is analyzed to be 95.43%. One planetary gear reducer is designed to illustrate the design methodology. Based on the proposed methodology, all planetary gear reducers for elevator can be synthesized.