Considerable efforts have been made to develop hematite as a promising material for photoelectrochemical (PEC) water splitting. However, the fast recombination of carriers in the bulk and on the surface greatly constrains the solar-to-chemical fuel conversion efficiency. Herein, a precise method was utilized to alleviate the recombination by constructing p-n junction of CaFe2O4/alpha-Fe2O3 and further modifying with Co3O4. The structural information and chemical composition of the ternary compound were systematically characterized. The photocurrent density at 1.23 V vs RHE (reversible hydrogen electrode) of the photoanode increased by five times compared to the bare alpha-Fe2O3, and the onset potential also shifted negatively to 0.6 V vs RHE. The formation of p-n junction and surface Co3O4 modification were proven to enhance the charge separation in the bulk and on the surface, respectively. Also the Co3O4 played a bifunctional role of passivating the surface states and accelerating the water oxidation kinetics. .