The invention discloses a high-power fuel cell stack tester humidification module, which comprises a water supply system, a flash evaporation system, a water vapor mixing system and a control system.The control system is connected with control components connected with the water supply system, the flash evaporation system and the water vapor mixing system. A water storage component in the water supply system is connected with an injection pump and an atomization component in sequence through a pipeline. The flash evaporation system comprises a flash chamber and a heating plate. The atomization component is fixedly arranged above the heating plate. The water vapor mixing system connected with the flash evaporation system comprises a mixing chamber, a baffle plate in the mixing chamber anda shunt ring under the baffle plate. The shunt ring is connected with a gas supply pipeline that feeds a gas to be humidified; the gas to be humidified passes through the shunt ring and enters the mixing chamber, is mixed with the water vapor and then, flows through the baffle plate. The humidification module can realize high uniformity of water atomization; by adjusting the heating plate throughan upper computer, fast water evaporation is realized, and energy consumption is reduced; accurate control of temperature and humidification of flow gas is realized, and fast conversion from high humidity to low humidity is realized; and response speed is fast.