The total dose, single event particle and coupling irradiation effects of GaN-based DC/DC converter were investigated. The variation of output voltage, output current and output efficiency of DC/DC converter with different irradiation conditions under specific load and voltage conditions were discussed. The experimental results show that the DC/DC converter using GaN MOSFET switch tubes exhibits excellent anti-irradiation performance under total dose, single event particle and coupled irradiation conditions, i.e., the performance of output voltage, output current and output efficiency of the device do not degrade significantly under three different irradiation conditions. The GaN-based DC/DC converter exhibits super resistance to total dose irradiation greater than 1 kGy (Si) and resistance to single event particle with LET ≥ 75 MeV·cm2·mg-1, which indicates that this type of DC/DC converter has great potential applications in the future for power supply systems in aviation and aerospace.