Chitosan modified silicon dioxide aerogels were prepared by sol-gel method and atmospheric drying method. The materials were characterized by Scanning electron microscope (SEM), infrared spectroscopy (FTIR), electronic universal testing machine, thermogravimetric analysis, static contact angle measurement, etc., the effect of chitosan on the structure and properties of pure silica aerogels was analyzed. The results showed that the silica aerogel modified by chitosan had milky white particles on its surface, and the addition of a small amount of chitosan powder made the silicon dioxide spherical particles more tightly linked to form a continuous network structure, it is more porous than silicon dioxide aerogels, and the addition of chitosan makes the structure of the material more stable. Compared with silicon dioxide aerogels, the hydrophobicity and thermal stability of chitosan-silica aerogels are improved, the compression resistance of the material was obviously enhanced by 66.2%, and the material had good adsorption ability for many kinds of oil and organic solvents, the maximum adsorption capacity of modified silica aerogel is 12 times of its own weight. In conclusion, the chitosan modified material can improve the absorbability and repeatability of oil-water mixture, and achieve the goal of low cost and efficient oil-water separation.