Abstract: In order to investigate the relation between growth of fused silica initial damage and numbers of laser pulse, the damage sites located on exit surface of conditioned fused silica were irradiated with 355 nm pulse laser. After each shot, photograph of growth of the damage site was taken and the area of the damage site was measured. By comparing with the case of growth of unconditioned fused silica damage sites, experimental results show exponential growth in the lateral size of damage sites located on exit surface with shot number in both the case of conditioned and the case of unconditioned, whereas the growth of conditioned silica damage sites are more rapid than the growth of unconditioned silica damage sites. Laser condition can effectively improve laser damage threshold, but it can reduce resistance of fused silica to damage growth.