Pure Cu2O particles were synthesized by hydrothermal method, and Cu2O-CuO composite particles and pure CuO particles were synthesized by oxidation reduction method. The structure and composition of the products were characterized by field emission scanning electron microscopy (FESEM) and X ray diffraction (XRD), and the results indicate Cu2O-CuO composite particles present a cubic spiny structure. The experimental result of surface photovoltage shows Cu2O-CuO composite particles have a special transient photovoltage and can detect the light source change keenly. The photocatalytic experiment shows that Cu2O-CuO composite particles have a good photocatalytic activity.