In high-power laser facilities, contaminants on the surface of optical components can reduce beam quality and even induce damage to optical components. For the contaminated large-aperture vacuum separator (430 mm×430 mm) coated with SiO₂ sol-gel antireflection film in the facility, a Nd:YAG pulsed laser with a wavelength of 355 nm was performed in laser cleaning experiment. The experiment adopted a single-shot laser dry cleaning and a laser cleaning system assisted by an airflow replacement system. The influence of key characteristic parameters on in-situ laser cleaning was studied, and the process parameters that could be used for laser in-situ laser cleaning were obtained. The processing of optical elements was characterized by microscope, dark field imaging and image processing software analysis. The experimental results suggest that there is an optimal process window for laser in-situ cleaning of optical components. After the laser cleaning method assisted by airflow replacement, the laser cleaning ability is greatly improved compared with the simple single-shot dry laser cleaning. Therefore, the single-shot laser cleaning assisted by the airflow displacement system can effectively improve its cleaning ability and provide an effective means for the in-situ removal of contaminants on the surface of large-aperture optical components in high-power laser facilities.