For problems found in the overhauling and repairing of some sector gate locks，we analyze the two different structure forms of sector gate used in the lock.Through the manufacture performance,maintenance performance,anti-ship collision performance and service life of sector gate,we find that the traditional sector gate which is a combination of the angle steel,I-steel,U-steel is superior to the s ector gate which is a combination of the ball joint and seamless steel pipe.