Aiming at the problem that the rotor heat is difficult to dissipate during the operation of drive motor for vacuum dry pump, which causes the heat to be transferred to the bearing through the rotating shaft and the bearing to lock. Taking the 3.0 kW drive motor as an example, three schemes of induction motor (IM), permanent magnet synchronous motor (PMSM) and double salient permanent magnet motor (DSPMM) are designed respectively. The structure and electromagnetic scheme of the three motors are determined on the premise of ensuring that the three motors have the same size, power level, and rated speed. Based on the same cooling conditions, the temperature field and stress field of the key components of the three motors are simulated. The analysis results show that the rotor temperature rise of the DSPMM is lower during rated operation, and the bearing thermal deformation is the smallest, which can effectively reduce the risk of bearing lock during motor operation, and is more conducive to the long-term stable operation of the vacuum dry pump unit.