Co-doped FeS2 composites were successfully synthesized through a facile microwave-hydrothermal process. The products were characterized by X-ray diffraction, X-ray Photoelectron Spectroscopy, field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, and Raman spectroscopy. Cobalt doping didn't change the basic structure of pyrite FeS2. But the spherical FeS2 product changed into some aggregated laminar particles. The Co-doped FeS2 product exhibited higher absorption in visible-light region and the photocatalytic performance was greatly enhanced. The Co0.333Fe0.667S2 product could decompose 48.9 % methylene blue within 210 min, which was 36.5 % higher than that of the pristine FeS2.