The invention relates to a combined water film evaporative air-conditioning cooling device for a subway station. The current subway air-conditioning ventilation system is high in energy consumption, large in size, and high in engineering investment and operation cost. The device is provided with air inflow distribution control valves, a circulating water pump, water film evaporative cooling module units, an air-water separator and an air outflow collecting cover sequentially in an air inflow direction, wherein the water film evaporative cooling module units, a guide groove, the air-water separator and the air outflow collecting cover are connected into a detachable mobile water collecting tank. The combined water film evaporative air-conditioning cooling device is based on a water film evaporative cold source-free air-conditioning principle of heat and humidity exchange; a modular structure form is adopted, so that the device is convenient to transport, mount, and maintain, simple in system, flexible to control, and high in adaptability, and operates flexibly; the detachable mobile water collecting tank and the air-water separator are convenient to clean periodically, so that bacterial growth is reduced; the quality of treated air is improved; the loss of circulating water is reduced; the water treatment expense and operation cost are lowered; and a water resource is saved.