A Two-dimensional （2D） composite grating is proposed to reduce the reflection of the interface of the epoxy-resin-encapsulated silicon solar cell and improve its photoelectric conversion efficiency. The 2D composite grating is prepared by longitudinally stretching One-dimensional （1D） Polydimethylsiloxane （PDMS） grating together with plasma surface modification. Scanning Electron Microscope （SEM） characterization of the 2D composite grating shows that nanowrinkles are longitudinally and orderly distributed on the surface of 1D grating. Optical measurement and theoretical simulation consistently demonstrate the 2D composite grating has superior antireflective property to 1D grating. Electrical characterization shows adding the 2D composite grating onto the epoxy-resin-encapsulated Si solar cell as an antireflective coating can improve the photoelectrical conversion efficiency， reduce the adhesion of dust particles and enhance the surface hydrophobicity and the self-cleaning property of Si solar cell.