The study of the resonance characteristics of sub-wavelength gratings has always been one of the most important part of optics. In this paper, a sub-wavelength one-dimensional grating design based on Fano resonance is proposed. Compared with the guided-mode resonance, the Fano resonance has stronger near-field enhancement, finer spectrum and higher sensing quality factor. The optical simulation software, FDTD Solutions, is used to simulate the structure of the grating. The parameters affecting the diffraction performance of the grating are studied in detail, including the period, refractive index and duty ratio of the grating. The simulation results show that Fano resonance lines have high resonance intensities, fine spectral lines and controllable resonance positions in the visible light region. Based on this discovery, the one-dimensional grating structures proposed in this work could be utilized as a wavelength selector with an accuracy of less than 1 nm.