The absorber with broadband and high absorption is the key for the utilization of solar energy. We designed a solar absorber based on a two-dimensional photonic crystal structure including an antireflective layer, in which Gallium arsenide (GaAs) is used as the absorbing medium and filled in the tungsten (W)-based circular empty cavity of two-dimensional photonic crystal with tetragonal lattice. The finite element method is used for the simulation and calculation, and the results show that in the wavelength range of 300--2500 nm, the average absorptivity of the absorber is 92.5% and the effective absorptivity is up to 94.9%. Moreover, the effective absorptivity of the absorber is 90.13% when the incident angle is 50°. The proposed structure has the characteristics of high absorption in the full solar spectrum, polarization-insensitivity and wide-angle absorption. These research results can provide a certain reference for the high-performance solar absorber.