The invention discloses an electricity-electricity hybrid fuel cell vehicle hydrothermal management system and a control method thereof. The electricity-electricity hybrid fuel cell vehicle hydrothermal management system comprises a fuel cell stack, a power cell system, a power cell thermal management system, a fuel cell cooling system, a controller and a detection unit, wherein the power cell thermal management system comprises a first electric three-way valve, a PTC heater, a second electric three-way valve, the power cell system, a second water pump, a third electric three-way valve, a radiator fan and a radiator, the fuel cell cooling system comprises a first water pump, the first electric three-way valve, the radiator, the radiator fan, the third electric three-way valve, a heat preservation water storage tank, the fuel cell stack and a condenser, the detection unit comprises two temperature detection units and a pressure detection unit, and the controller controls the working states of the PTC heater, the water pump and the radiator fan according to the detection results of the temperature detection units, so that low-temperature cold start and constant-temperature operationstate control of the fuel cell system and the power cell system are carried out.