The invention provides a method for introducing an AAO template as a nanometer grating to a solar cell structure, and discloses a thin film silicon solar cell double-trapping-light structure with AAO nanometer gratings on the surface and the bottom. A surface decreasing structure of the double-trapping-light structure is composed of AAO and ITO, and a back reflection structure is composed of AAO, ITO and Ag. FDTD solution software is utilized for optimizing structural parameters of the AAO. According to the double-trapping-light structure, surface reflection losses of a solar cell can be effectively reduced, the light path of photons with the long wavelength in an absorbed layer can be improved, and therefore light absorption of the thin film silicon solar cell within the range of 280 nm to 1100 nm is increased, and the absorption can be relatively increased to reach 74.44 percent. Due to the fact that the AAO is easy and convenient to manufacture, low in cost and suitable for mass production, it is predicated that in the near future, the AAO will certainly play a bigger role in application of the thin film silicon solar cell.