The fluorescence imaging technology is proposed for non-destructive detection of subsurface defects of fused silica optical elements. The subsurface defects of fused silica optical elements under different processing techniques are obtained by this method. Based on the damage properties of fused silica optical elements, the relationship between subsurface defects and damage properties of fused silica optical elements is analyzed. The results show that the damage threshold of fused silica optical elements is inversely proportional to the density of fluorescent defects, that is the samples with less subsurface fluorescence defects have high damage threshold. This shows that the technique can effectively evaluate the damage performance of fused silica optical elements. The results of this study have guiding significance for optical element processing technology.