A kind of speed regulating asynchronous magnetic coupler (SRAMC) based on cage rotor of asynchronous motor is designed. The relationship between torque and slip ratio is deduced. Based on this, the operation mechanisms of SRAMC′s starting characteristics, inflection point characteristics and synchronization characteristics are analyzed. The SRAMC finite element simulation model is established. The torque and speed curves, the relation between torque and slip ratio, and the corresponding speed regulation characteristic curves are obtained. Through the analysis of the established model and the above-mentioned curves, it is concluded that the starting and rated torques of SRAMC are proportional to the air gap magnetic density, the polar distance of permanent magnet and the square of coupling length, and its maximum torque is independent of the resistance of inner rotor cage strip. In addition, SRAMC has excellent speed regulation characteristics, and good energy saving benefits can be obtained when it is applied to centrifugal load.