A broadband antirelective Si0, coating with high transmittance and good hydrophobicity in thevisible range was successfully prepared by template-free sol-gel method.The refractive indices of the bottomlayer and top layer of the coating are 1.34 and 1.15 , respectively. The bottom layer was prepared by mixing Si0sols catalyzed by acid and base, and the sol of the top layer was prepared by using hexamethyldisilazane( HMDS) as modifier, which is composed of trimethylsilanized Si0, nanoparticles. According to the design requirements of the optimized film system, suitable technological parameters were selected to prepare thedouble-layer coating. The test results show that the average transmittance of the Si0, double-layer coating in thevisible light region is 98.64%,and the static water contact angle can reach 134°.