The invention provides a current source type phase modulator variable frequency starting commutation lead angle piecewise control method which comprises the concrete steps that a commutation lead angle of 30 degrees is used when a current source type phase modulator is started; commutation failure is judged through a detection system, the commutation lead angle of 30 degrees is maintained if the commutation failure is not detected, and the closest thyristor seamless switching time point t0 is found when the commutation failure is detected; and the commutation lead angle is switched to 60 degrees. The method is simple and convenient in practical application without redundant algorithm control; the problem of thyristor commutation failure can be effectively avoided, the starting efficiency of the phase modulator can be improved, the starting time can be shortened, the whole control process only needs one time of switching of the commutation lead angle and the redundancy of thyristor operation times can be avoided; and commutation lead angle piecewise control is used so as to have high practical engineering application value.