The invention relates to a soft start type asynchronous motor. When the asynchronous motor is started, the slip ratio s is the maximum, the rotor electromotive force E is also the maximum, the starting current is quite high, and the starting torque is low since that the electromagnetic torque is determined by the active component of a rotor winding current; in starting, when s is equal to 1, the rotor leakage reactance is the maximum, the rotor side power factor is quite low, the active component of the rotor winding current is quite low in starting, and the starting current is high; consequently, leakage impedance voltage drop of a stator winding is increased, the air gap magnetic flux of each pole is lowered, and starting torque is further lowered, so that motor power needs to be increased in heave load starting equipment, and quite high electric energy waste is caused consequently; the soft start type asynchronous motor solves the above problems perfectly. The asynchronous motor comprises a motor, a soft starter shell, a soft starter, bearings and end covers. The asynchronous motor can realize no-load start and automatic loading, can reduce motor power of the heavy load start equipment by more than half, and can be widely applied in power-saving operation of the equipment of oil fields, mines, steel and iron, cement, paper making, chemical engineering, pumps, fans and the like.