Abstract: With the rapid improvement of the industry, the air pollution in our country is increasing seriously. As the exterior walls of the buildings are exposed to the air all year round, the various kinds of pollutants attached to the walls are difficult to remove. Therefore, the protective measures of building walls have attracted more and more attention. In this paper, a self-cleaning coating for building wall protection was proposed, which was mainly the compound of the polydimethylsiloxane (PDMS) and hydrophobic SiO₂. The prepared coating was sprayed on the building wall and cured at room temperature to form a self-cleaning coating. Through the analysis of the combination mechanism of the coating and building wall, it shows that the coating has a strong adhesion to the wall. Due to the super-hydrophobic property of the coating, the particulate pollutants and the liquid contaminants attached to the wall are easily cleaned through water flow. Furthermore, the experiments also show that the self-cleaning effect of the coating do not change significantly even after five months in the outdoor environment.