The invention relates to a steam reinjection type gas turbine power generation method and device based on solar energy and waste heat recovery. Purified air enters a gas compressor to be pressurized, the compressed air enters a heat regenerator or enters the heat regenerator after being mixed with saturated steam, the heat regenerator heats the work medium gas through tail gas of a gas turbine, and part of waste heat is recovered. The work medium gas heated by the heat regenerator enters a combustion chamber to be combusted together with fuel after being heated by a solar heat collector, generated high-temperature flue gas enters the gas turbine to do work, tail gas sequentially enters the heat regenerator and a steam generator, the tail gas waste heat is recovered by the steam generator again, the saturated steam for reinjection is generated, and steam in the tail gas is recovered after being condensed. When solar radiation does not exist or radiation is not sufficient, the work medium gas directly enters the combustion chamber through a bypass. The saturated steam is re-injected into a gas turbine system, the power consumption of the gas compressor is reduced, and the power generation efficiency and the specific power of the gas turbine are improved; and meanwhile, solar energy is utilized to heat the work medium gas, and the consumption of the fuel is reduced.