This paper referred to a vision system based on the principle of stereoparallax range finding, which has been applied in a Automatic Guided Vehicle System(AGVS)successfully. Two image of a scene are taken by the left and right pick up cameras at same time and acquired by the computer through video interfacerespectively. The algorithm calculated the distance between target point and the pick-up camera is presented. Then. a map for making path plan can be obtained.