The membrane humidification system of the air conditioning unit is a system that delivers water from the water tank to the top of the humidifier through a water sprinkler. The water is evenly sprayed onto the top of the membrane, and the sprinkler ensures that the water is evenly distributed onto the membrane material. Under the action of gravity, the water infiltrates downwards along the membrane material, wetting all layers inside the membrane and being absorbed by the membrane material, forming a uniform water film. When dry air passes through the membrane material, there is a large area of contact between the dry air and the wet membrane surface, and the moisture fully absorbs the heat of the air and vaporizes and evaporates, thus achieving the purpose of humidifying the air. During this humidification process, the humidity of the air increases and the temperature decreases, but the enthalpy value of the air remains unchanged.