Provided is a middle-low air pressure down-hole hammer. The middle-low air pressure down-hole hammer comprises a back joint, a check valve, an air-distribution rod, a piston, an internal cylinder, an outer casing pipe, a clamping ring, a guide sleeve, a plug, a first spring, a rubber stick, a lateral pin, a pin-hanging type drill and a pin-hanging type front joint. The check valve is a one-way valve and provided with a valve seat and a second spring. The piston is a long-and-thin-shaped piston with a hole path. The air-distribution rod and an air inlet seat at the back end of the check valve are of an integrated structure. The internal cylinder is placed outside the air-distribution rod and the piston. In the process of piston motion, the matched end of the piston and the air-distribution rod is in the internal cylinder all the time, a cavity is formed between part of the piston and the outer casing pipe, and other parts of the piston are matched with the internal cylinder. According to the middle-low air pressure down-hole hammer, the air distribution rod and the valve seat of the check valve are integrated, the structure is simple, the functions of locating, vibration damping and air suction can be achieved, and stability and reliability are achieved in the process of work. Contact portions of the piston and the internal cylinder are reduced, and therefore the internal cylinder is wear-resisting, and working pressure ranges of the hammer are wide.