In order to meet the requirements of high precision and miniaturization of surface-mount for printed circuit boards, realize the SMT production of fully automation, high reliability and high speed, a new kind of automatic optical inspection system was researched. The device was mainly composed of optical path system, the linear array camera, quantitative storage unit, template library, dedicated high-speed image processing unit and monitoring unit, and other modules, which could realize functions of equipment calibration, defect recognition, alignment correction and compensating for the position, and so on. The experiments prove that the system can satisfy the real-time detection requirements for high precision and high speed mounting of the high precision of printed circuit boards in production, which achieves better detection result.