A new method for preparing a coating composed of micro-nano SiO2 particles on polyimide surface by dispersive SiO2 nanospheres in silica sol using St?ber and sol-gel methods was studied. The coating is used to increase the service life and erosion resistance of Kapton films to atomic oxygen (AO). Firstly, St?ber nanospheres were prepared with TEOS under alkaline conditions; then, silica sol was prepared under acidic conditions with 3-aminopropyltriethoxysilane (APTES). The nanospheres were uniformly dispersed into the sol, and the coating with SiO2 particles was prepared on the Kapton surface by dip coating method. Before coating, Kapton films were hydrothermally treated with low concentration NaOH. The simulation experiment was conducted in an AO environment with a beam density of 1.43×1016 atoms/(cm2.s) and an irradiation time of 6 h. The surface morphology of samples before and after experiment was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). After AO irradiation, the mass loss and AO erosion rate of pristine Kapton were 1.39 mg/cm2 and 3.17×10?24 cm3/atom, respectively, and the Kapton surface was severely eroded. For coated Kapton samples, mass loss and AO erosion rate decreased to 0.10 mg/cm2 and 0.22×10?24 cm3/atom, respectively, which was only equivalent to 6.9% of pristine Kapton. Using the method of combining St?ber and sol-gel, the SiO2 content was increased in the prepared coating. Simulation experiments show that the coating improves the AO erosion resistance of Kapton. This method is simple and practical, and has certain research significance for AO protection of polymer materials in long-life spacecraft.