The invention discloses a limit valve capable of controlling the jack stroke. The limit valve comprises a valve body mounted between a piston rod and an oil cylinder; a mounting hole is formed in the outer surface of the piston rod; the valve body is mounted in the mounting hole and comprises a reset spring, a conical valve, a valve seat, a thimble, a steel ball and an O-shaped ring, the reset spring is mounted at the hole bottom position of the mounting hole, the valve seat is arranged in the mounting hole, the conical valve is arranged in the valve seat, the lower end of the conical valve is inserted into the reset spring, the thimble is also arranged in the valve seat, a mounting groove is formed in the outer surface of the valve seat, and the O-shaped ring is fixedly arranged in the mounting groove. The limit valve has the benefits that after the completion of mounting, the limit valve has a maximum position limiting function under no load and full load of the air cylinder; through the adoption of the limit valve, the operation of forming an opening in a cylinder body is eliminated, and the service life is long.