The optical surface defects have a significant impact on functions and reliability of the whole optical system. In recent years, with the great attention on research of large-scale high-power solid-state laser device at home and abroad, the detection of optical surface defect has also been highly valued. Through continuous exploration, defect detection technology has made some achievements, but there are still some urgent technical problems to be solved. In this paper, the technology situation of optical surface defect will be summarized in two aspects: the surface cleanliness and surface flaws. Moreover, the technical difficulties and the problems which are currently facing will be analysis.