The invention discloses a cylinder cover with a water-cooling air compression function. The cylinder cover is used for being installed on a cylinder of an air compressor and provided with a bottom surface sealed with the cylinder, the cylinder cover is internally provided with an air inlet channel, an air outlet channel and a cold water cavity, and the air inlet channel is of a cylindrical structure, is vertically arranged at the center of the cylinder cover and is an up-and-down through channel; an annular sealing mechanism is arranged at the bottom edge of the air inlet channel, an annular inner air port is formed in the outer edge of the sealing mechanism, and the outer edge of the inner air port is provided with an annular sealing panel which is used for being sealed with the top surface of the cylinder; an arc-shaped air connection port is formed in the outer side of the sealing panel, and the inner air port communicates with the air connection port through the air outlet channel; the sealing mechanism is used for being pressed on a combined air valve and separates an air inlet of the combined air valve from an air outlet of the combined air valve, the air inlet of the combined air valve is connected with the air inlet channel, and an air outlet of the combined air valve is connected with the air outlet channel through the inner air port; and the cold water cavity is arranged between the outer wall of the air outlet channel and the outer wall of the cylinder cover and surrounds the air outlet channel.