The invention discloses a pulse width modulation method for a five-phase inverter. The method mainly controls the on-off states of switching devices on the five-phase bridge arms of the inverter according to a given reference voltage in combination with an optimized offset. By optimizing the offset, the method enlarges a modulation range and improves the utilization ratio of DC bus voltage. The modulation method is based on an idea of energy transfer, does not consider whether a load is symmetrical, and can be easily generalized to an inverter for driving a fault-tolerant operation motor.