The invention belongs to the photovoltaic field, provides a composite antireflective film for solar cells and a preparation method thereof, and particularly relates to a method for coating a SiO2/TiO2 composite antireflective film by using a sol-gel combined with dipping and lifting process. The preparation method includes the steps of designing a TiO2 thin layer and a SiO2 thin layer alternative composite antireflective film for the solar cells, then using butyl titanate and ethyl silicate as precursors and using ethyl alcohol as a solvent to respectively prepare TiO2 sol and SiO2 sol, alternatively coating the TiO2 sol and the SiO2 sol on common glass by using of the dipping-lifting process, and finally, carrying out heat treatment to obtain the composite antireflective film for the solar cells. The preparation method is simple in process and easy to control and convenient to achieve. The thin film coating is even, and the composite antireflective film is good in light-admitting quality.