Abstract: In the application of the modern laser technology, subsurface damage (SSD) on optical components generated in the manufacture process is one of major sources for laser damage. Subsurface damage detection is becoming a hot topic in optical manufacture society. With the apparatus in the lab, non-contact white light interference theory was used to detect subsurface damage of K9 optics. 3D map and portrait slice diagram were obtained to precisely determine the depth of subsurface damage and damage density at different depths. This method is nondestructive, accurate and convenient to use.