This paper introduces the basic structure of a long depth of field array optical components defect detection system used in SG-Ⅲ. The phase modulation used on the system aperture can realize the depth of field extension effect, which can achieve large depth of field imaging detection from 3~13 m object distance. The performance index, design ideas, design result and simulation evaluation of the optical detection system are expounded. It can achieve the defect simultaneous detection of the array optical components in longitudinal range of 3~13 m by using proposed system.