Abstract: The laser induced damage threshold (LIDT) and the particle contaminations of the large-aperture optics such as beam sampling grating (BSG) which is likely to generate stimulated Brillouin scattering, were measured after chemical etching and ultraviolet (UV) laser cleaning, with the BSG side under the radiation of 355 nm laser. The results show that the LIDT of the BSG side increases by 78% after chemical etching, which is almost equal to that of light pass surface, but it is only about 56% after UV laser cleaning. By comparing the particle contaminations coming from the side of the optics in two ways, it is found that the UV laser cleaning can also improve the laser threshold for the particle contamination generating, and has little influence on the optics performance. Also, we prove that the UV laser cleaning has a better security and applicability than the chemical etching through the analysis of morphologies and the influence of optical clear aperture.