From the view point of mechatronics, a method to determine the rated voltage of lowpower lowspeed directdrive squirrelcage asynchronous motor (LLDSM) was presented. The relationship among the rated voltage, the maximum torque multiple and the maximum output voltage of variable frequency power supply was researched. The selection principle of pole number and slot number of LLDSM was discussed, and the harmonic content of air gap magnetic field in different poleplot match was simulated and analyzed. Moreover, the prototype of LLDSM was tested, and the relationship curves of motor torque versus current and voltage were measured. The experimental data were studied and analyzed to verify the correctness of the theoretical analysis.