Pure ZnO and doped-ZnO with Sb nanoparticles, are prepared by chemical coprecipitation. X- ray diffraction(XRD) results indicates that the wurtzite structure of ZnO is formed while the amount of antimony is less than 5wt%. According to the test results of gas sensitivity and conductivity of ZnO and Sb doped-ZnO sensors , it is found that the sensitivity was influenced greatly by different sintering condition and is improved by doping the Sb,the conductive apex of Sb doped ZnO is disappeared. The result of XPS and the defect of sample can explain the changes in conductivity and gas sensitivity .