Abstract: Ni(OH)₂ and Zn(OH)₂ precursor were prepared by sol-gel method. Ni(OH)₂ gel was sintered into NiO powder by a tube furnace and vacuum sintering furnace respectively. Zn(oH)₂ gel was sintered into ZnO powder by the tube furnace. The samples were characterized by X-ray diffraction. The photocatalytic degradation of methyl orange in the catalysts aqueous suspension was studied. The results show that the photocatalytic property of the NiO treated under 0. 5Pa partial pressure of oxygen is higher than untreated. It explains proper oxygen vacancies introduced can enhance the separation of electron hole pair of catalysts. The composite powder of ZnO and NiO treated at 0. 5Pa -vacuum with the complex mass ratio 2: 1 has a maximum photodegradation rate 93. 099%. It indicates the presence of oxygen vacancies and p-n junction can improve the photocatalytic property.