The nano powder NiO is prepared by hydrothermal methord,and is doped with WO3.The microstructure is analyzed by XRD.The gas sensitivity of doped materials is detected.The results show that the sensitivity of WO3-doped NiO sensor is higher than pure NiO sensor and the sensitivity of 6 % quality fraction WO3-doped NiO is best,which highest sensitivity to Cl2 is 37.5 at 350 ℃,while its sensitivity to H2S is 30.4 at 200 ℃.So the sensor has selectivity to different gases at different temperature.Also the sensor ...