The invention provides a graphite self-lubricating device for sealing a piston rod of an air cylinder. The graphite self-lubricating device comprises the piston rod, a cylinder cover, a rod sealing assembly and a self-lubricating assembly, wherein the piston rod is connected with the cylinder cover through the rod sealing assembly and the self-lubricating assembly; the rod sealing assembly comprises a lip-shaped seal ring, an O-shaped seal ring, a rectangular slide ring and a dust ring; the self-lubricating assembly comprises a rubber sleeve, a graphite ring, a pressure ring, a locking screw,a fastening screw and an end cover; the outer wall of the graphite ring is connected with the inner wall of a groove in the rubber sleeve; the outer wall of the rubber sleeve is connected with the inner wall of the cylinder cover; a second end surface of the rubber sleeve is connected with a first end surface of the pressure ring; the lower half part of a second end surface of the pressure ring isconnected with an end surface of the dust ring; the inner wall of the pressure ring is connected with the piston rod; the outer wall of the pressure ring is connected with the inner wall of the cylinder cover; and the fastening screw is connected with the upper half part of the second end surface of the pressure ring through the end cover. The graphite self-lubricating device solves the problem that when oil is adopted for lubricating, the abrasion cannot be reduced in time, and improves the working efficiency and the working environment quality.