Aiming at the disadvantages of poor heat dissipation condition of cage rotor and easy demagnetization of permanent magnet, an outer squirrel cage rotor magnetic coupler (OSRMC) is proposed. Based on the composition and operation principle of OSRMC, the thermal analysis model and loss principle are given, and it is demonstrated that when the slip of OSRMC is 33.3%, the generated thermal power consumption is the maximum (4/27 times of the rated power). Based on the principle of heat transfer, the two main heat exchange modes and the differential equation of heat conduction of OSRMC are given, and the finite element simulation results of OSRMC are obtained based on the cluster analysis method and the domain partitioning method. The results show that: the main heat exchange mode of OSRMC is thermal convection, and its main temperature rise is located at the coupling between the cage and the permanent magnet and gradually decreases along the axial direction. The calculation accuracy of cluster analysis method is equivalent to that of area division method, but the calculation speed of area division method is fast and the grid division is more difficult.