Spectral selectivity absorber is a key component in the solar collectors, which absorbs solar energy and converts it to thermal energy by heating liquid water. Metal nanowire arrays (NWAs) have potential to be used as solar collector because of good optical absorption in the visible region. In the paper, we use finite-difference time-domain (FDTD) solutions to calculate the optical absorption and spectral selectivity of nickel (Ni) NWA/AAO composites. By changing the length (L), fill-factor (FF), and surface roughness, we simulate the optical absorption and the spectral selectivity in terms of structural parameters of Ni NWA/AAO composites. Results demonstrate that Ni NWA/AAO composites with the length of 2 μm and the fill-factor of 0.13 (the diameter is 0.04 μm) have good optical absorption and spectral selectivity,and rough surfaces is better for higher conversion efficiency of Ni NWA/AAO composites.