High temperature convertion online measurement of oxygen isotopic composition of perchlorate can provide important clues to recognize the origin of perchlorate, trace the subsequent migration and transformation processes of perchlorate, and prevent the pollution of perchlorate. The accurate research on the effects of reaction temperature, sample size and sample type on analytical precision, and the research on preparation and purification procedures of field perchlorate samples are important to expand the application of this method. The results indicate that the reaction temperature has a significant effect on analytical precision, so the reaction temperature must be controlled at 1325℃. The sample size has a slight effect on analytical precision, with the least sample size of 0.25 μmol ClO4-. This method can be applied to different types of perchlorate, with a good analytical precision of 0.5‰. Both the method corrected by USGS37, the international standard of perchlorate, and linearity correction of multiple international standards of oxygen isotope are used to correct the test results of field perchlorate samples. The method corrected by USGS37 will make a major inaccuracy, especially when oxygen isotopic composition of samples have significant differences with the standard. Based on the pretreatment method of ClO4- concentrated and extracted by the bifunctional ion-exchange resin A530E, the test results of field perchlorate samples are within a good analytical precision of 0.3‰.