Abstract: Based on the issue of formaldehyde pollution in indoor air environment, silica-based tannin composite material(DMSNs-tannin) was prepared using forest by-product tannic acid as the adsorption source, dendritic mesoporous silica nanoparticles(DMSNs) as the matrix, and amino modified silica(DMSNs-NH₂) as the intermediate. When the addition amount of tannic acid was 0.3, 0.4, and 0.5 g, the prepared composite materials were DMSNs-0.3, DMSNs-0.4, and DMSNs-0.5, respectively. The structure was characterized by SEM, TEM, nitrogen adsorption/desorption isotherms, FT-IR, and TG analysis. The effect of different tannin loading amounts on its formaldehyde adsorption performance was investigated, and the adsorption kinetics was explored. The research results indicated that the composite material had rich pore structure and high thermal stability. Compared with DMSNs-NH₂, DMSNs-tannin had better formaldehyde adsorption performance. The DMSNs-0.5 had the highest loading capacity of tannic acid, reaching 23.60%, with a loading efficiency of 47.33%, and a formaldehyde adsorption rate of 86.19% after 6 hours adsorption. The special mesoporous structure of DMSNs provided channels for the diffusion of formaldehyde. Their adsorption process was in accordance with the quasi second-order kinetic model, indicating that their adsorption of formaldehyde was mainly chemical adsorption, which was related to adsorption sites, demonstrating a composite adsorption process of adsorption on the surface of composite materials and diffusion within particles.