A fluid pump driven by compressed air comprises a central body, a central shaft, a reversing shaft, membranes, air chambers, fluid chambers, a valve ball, a fluid inlet, a fluid outlet, etc. The central shaft and the reversing shaft are installed on the central body; a membrane is respectively installed at the two ends of the central shaft; the membranes are fixed at the two ends of the central shaft by membrane splints; and the two ends of the reversing shaft are also respectively connected on a left membrane splint and a right membrane splint. The membranes are clamped between a shell and apump body; and the two membranes are sealed into a left air chamber, a right air chamber, a left fluid chamber and a right fluid chamber between the shell and the pump body; the reversing shaft controls the horizontal movement of a piston and respectively charges the two air chambers, and pushes and presses the fluid chambers by the membranes to lead the fluid to flow from the fluid inlet into thefluid chambers and then out of the fluid outlet. As the fluid pump which is driven by compressed air is provided with the reversing shaft, the movement of the piston is directly controlled by the compressed air but does not fail, and the maintenance and installation are convenient.