in many industrial situations, edge detection of 3-D objects is frequently required.Typical examples are found in dimension control and machine vision applications .As technology advances, the capability of computers has greatly improved. This paper describes our system used to inspect objects and the method used to find the edges for those objects with planar and cylindrical faces from a huge set of cloudy points. First the systems are based on opto-electronic techniques and hence are non-contact. The system is designed for a small objects less than 2 x 2 x 2 cm. The edge resolution is based on the principle of spacial geometry of a triangle in the cartesian coordinate system. The system can be considered scanning linearly with a rotation stage of a mirror,on the other hand the object circumferentially rotate on a turntable. After obtained surface profile of 3-D objects,we then apply for a geometrical method to find the edges. The performance of the systems is demonstrated with different sizes test objects. in many industrial situations, edge detection of 3-D objects is frequently required. Tip paper examples are found in dimension control and machine vision applications. As technology advances, the capability of computers has greatly improved. This paper describes our system used to inspect objects and the method used to find the edges for those objects with planar and cylindrical faces from a huge set of cloudy points. First the systems are based on opto-electronic techniques and hence are non-contact. The system is designed for a small objects less than than 2 x 2 x 2 cm. The edge resolution is based on the principle of spacial geometry of a triangle in the cartesian coordinate system. The system can be considered scanning linearly with a rotation stage of a mirror, on the other hand the object circumferentially rotate After obtaining surface profile of 3-D objects, we then apply for a geometrical method to find the edges. The performance of the systems is rendered with with differ ent sizes test objects.