In order to analyze the influence of rotor slot opening depth and slot combination on the rotor loss of threephase variable frequency asynchronous motor, ANSYS Maxwell was used to analyze the rotor loss of a 10pole 1 100 kW threephase variable frequency speedvariable induction motor with abnormal noload loss. Motor models with different rotor slot opening depths and slot combinations were built. In combination with the theory of harmonic magnetic field in the motor, the losses of rotor cores and rotor bars of the motor models with different rotor slot opening depths and slot combinations were compared and analyzed. According to the results of simulation analysis, the prototype was improved. The results of the prototype test proved the correctness of the simulation calculation, which could provide reference for the design of the relevant motor.