Laser-induced optical damage often determines the service lifetime of an optic components in a high power laser system.A set of fused silica windows were artificially contaminated by sputtering the thin film material（Stainless steel）onto the surface to simulate target chamber contamination of optical components.The samples were tested by R/1 and S/1 at 355 nm with a SAGA-S laser to measure the damage threshold.The value of the damage threshold tested by S/1 is relatively accurate by comparing the S/1 and R/1 tests.The growth in lateral diameter and depth has an exponential relationship with the shot number of times.And experimental results show that the exponential growth coefficient of lateral diameter of sample is larger by 41% than that of the clear fused silica.The exponential growth coefficient of depth is larger by 39% than that of the clear fused silica.The speed of the lateral diameter damage growth slowed down and stopped after 20 shots.