A novel biomass carbon (BC) modified Z-scheme g-C3N4/Co3O4 heterojunction photocatalyst (BC/g-C3N4/Co3O4) has been constructed via a facile approach. In addition, various kinds of characterization methods, including TEM, XPS, UV–vis DRS, VSM, photoluminescence spectra, photocurrent response, electrochemical impedance spectroscopy, etc. are applied to investigate the morphology structure, optical property, magnetic properties and electronic properties of BC/g-C3N4/Co3O4. The BC/g-C3N4/Co3O4 is applied as novel photocatalyst to degrade various pollutants and it exhibits remarkable photocatalytic activity and stability as compared to pure g-C3N4 and Co3O4. Furthermore, the BC/g-C3N4/Co3O4 can be effectively separated from solution in favor of practical applications.