The invention relates to the technical field of hydroelectric generation, in particular to a water-light-hydrogen complementary microgrid power generation system and method. The system comprises a water-light complementary system composed of a hydroelectric generation system and a photovoltaic power generation system, a hydrogen energy storage system, an AC/DC device, a DC/AC device and a hydrogenfuel cell, wherein the power supply output end of the water-light complementary system is connected with the power supply input end of the hydrogen energy storage system through the AC/DC device, thehydrogen outlet of the hydrogen energy storage system is connected with the hydrogen inlet of the hydrogen fuel cell through a pipe, and the power supply output end of the hydrogen fuel cell suppliespower to a load through the DC/AC device. Excessive electric energy generated by the water-light complementary system is subjected to water electrolysis hydrogen production, electric energy is provided when power supply is insufficient, the renewable resource utilization rate is effectively increased, the operation and maintenance cost is reduced, and the power supply is more stable.