Abstract: An online inspection apparatus of optics damage in large scale laser facility is developed applying darkfield imaging technology. Experiments were carried out on a multipass amplifier. Optical defects, such as film damage, selffocusing filament and cranny on optical elements are inspected. Experimental results show that this apparatus can be used for online inspection of optics damage. Further improvements. that the image aberration should be decreased and the inspection range be extended are proposed.