Abstract: The motor rotor with the electric resistance speed regulation would have soft mechanical features with high energy consumption, unstable startup, high f ault rate and other shortages.A chopper cascade speed regulation system was designed.In order to improve the accuracy of the static speed regulation and to have goo d dynamic features, the double closed loop control with the current negative feedback and the rotary speed negative feedback was applied to the system.With the regul ation of the regulator, the rotary speed astatic system was finally achieved.The speed regulation scope of the system was wide and the rotary speed could be continuou sly regulated from 9501 350 r/min.The actual rotary speed during the stage jump input period could trace the given rotary speed and there was no error during the stabil ized period.During the constant speed operation, the motor could be smoothly in a natural characteristic curve and would have a full new function of the stepless stable speed regulation.