Abstract: This paper introduces the main preparation of WO₃ doped NiO nanometer powders and its VOCs gas-sensing properties.The XRD analysis shows that a new phase-- NiWO₄ exists in WO₃ doped NiO .With the doping concentration increasing,the diffraction peak half-width of NiO increases markedly. It suggests the doped WO₃ impedes the growth of NiO grain during the heat treatment.Testing with xylene, formaldehyde,toluene and ethanol(which concentration are all 50×10^-6),indicates that the gas sensitivity of NiO is improved evidently by doping WO₃.When the doping amount is 5%,the maximum sensitivity to xylene is 26.4,the response time is 4s;when the doping amount is 10%,the maximum sensitivity to formaldehyde is 4.67,the response time is 6s.