The system design of detecting SO-type components’ pin of coplanarity is introduced. The design of machine vision detect system is discussed. Nondestructive testing SO-type components’ pin of coplanarity is realized by using image processing technology and target identification Technology. Face of pins and base level are placed on a same plane. A clear image about face of pins and base level is obtained. The distance between them is measured out. On this basis, qualification of pin’s coplanarity is judged.