The influence of nano surface two-dimensional periodic half-round grooves on the enhancement of light absorption in silicon film solar cell is studied with the finite-difference time-domain method. The result shows that the broadband solar spectrum absorption is enhanced. The light optical absorption in Si thin-film cell is enhanced by optimizing the thickness of SiO2 anti-reflection film and the radius of half-round grooves, and the total integrated absorption of solar spectrum wavelength in a range from 300 nm to 1000 nm is about 117% greater than that of single silicon thin film.