Fused quartz optical material is a kind of new and high technology products, which has important applications both in aerospace and in daily life. The manufacturing cost and the complexity of manufacturing process are far more than other similar products because of its manufacturing difficulty. So the quality of finished products becomes the problem that people take the most attention to, in which subsurface damage detection is of special importance. Organize several commonly used surface damage detection methods and principles. The advantages and disadvantages of several methods are analyzed. And on this basis, this paper discusses the feasibility and accuracy of using confocal fluorescence microscopy to detect the optical element and dart layer damage. Using confocal laser scanning microscopy to detect fused quartz glass specimen surface damage is carried out. Using two kinds of fluorescent quantum dots respectively, the surface damage of the specimens tomographic images is obtained. Through testing the specimens we obtain distribution images of the surface damage. Using Image- Pro Plus 6.0 software processing, the scope of distribution density is got. Basic rules of sub-surface damage are concluded quantitatively.