The invention relates to a high-pressure air pump, and belongs to the field of high-pressure air pump manufacturing. The high-pressure air pump comprises a pump cover, air cylinders, pistons, a water cooling device and a pump seat. The air cylinders are composed of the first air cylinder, the second air cylinder and the third air cylinder, the diameters of the first air cylinder, the second air cylinder and the third air cylinder are gradually reduced, the first air cylinder, the second air cylinder and the third air cylinder are coaxially arranged, the pistons are composed of the first piston, the second piston and the third piston, the diameters of the first piston, the second piston and the third piston are gradually reduced, and the first piston, the second piston and the third piston are arranged in the first air cylinder, the second air cylinder and the third air cylinder respectively. The water cooling device is arranged between the second air cylinder and the third air cylinder. The high-pressure air pump further comprises a water cooling detecting system, an automatic lubricating system and an automatic drainage system. The high-pressure air pump has the advantages that the output work pressure is high, the heat radiation structure is designed, the heat radiation effect is good, and the high-pressure air pump can continuously work for a long time; the high-pressure air pump is suitable for being driven by a motor, pressure rising speed is high, and work efficiency is high; an air moisture filtering device is arranged, and the interior of the air pump does not need to be drained even though the air pump is used for a long time.