Drilling fluid defoamer is an organosilicone polyether copolymer, refined using a special process. It is specifically designed to solve defoaming problems in oil extraction and is mainly composed of organic hydroxyl compounds, silica, and dispersants. It exhibits good resistance to high temperature and pressure, as well as acid and alkali resistance. It is also highly effective in removing foam generated by surfactants, providing rapid and stable defoaming with a long-lasting foam suppression effect, while having no impact on oilfield processes.