Abstract: De-nickel silicon slag is the solid waste remaining after nickel and other metals are extracted from laterite nickel ore by acid leaching. In this paper, the physicochemical properties, humidity control and formaldehyde adsorption properties of De-nickel silicon slag from laterite nickel ore in Indonesia were studied. The results showed that the main mineral component of the De-nickel silicon slag from laterite nickel ore was amorphous silica. The chemical components contain a small amount of heavy metals in addition to silicon oxide, aluminum oxide, calcium oxide, magnesium oxide, and iron oxide. The pore size was mainly mesopores, the average pore size was 7.661 nm, the pore volume was 0.18 cm³/g, the specific surface area was 84.196 m²/g. It had good absorption/desorption performance and formaldehyde adsorption performance. Therefore, it can be used to develop high-performance humidity control and air purification materials.