Abstract: In conventional modulation strategy, there is a serious problem of uneven loss between inner and outer switches of a T-type three-level converter. When the converter’s modulation ratio is below 0.57, the inner switch temperature rise is significantly higher than that of the outer switch, and this issue is even worse during a low voltage ride through（LVRT） operation. It will threaten the long-term reliable operation of the converter. Therefore, a discontinuous pulse width modulation strategy based on optimal loss distribution is proposed. This adopts new switching sequences in corresponding regions of the space vector diagram. The clamping mode of each phase is to be clamped to the positive or negative pole so as to redistribute the current in outer and inner switches. This new modulation strategy adopts a five-stage wave mode. This can not only effectively improve the loss distribution of the inner and outer switches, but also enhance the efficiency of the converter. The balance of midpoint voltage is maintained through redundant small vector complementary sequences. The new modulation strategy has a unified carrier-modulation method. Finally, the effectiveness of the proposed loss distribution modulation strategy is verified by electrical-thermal co-simulation.