Abstract: Since there are a number of ways to measure hydrogen and oxygen isotopes by mass fractionation, this paper describes the comparison between three detection methods on four different water samples. Two different standards were used to calibrate the results. The results indicate that the Dual-inlet IRMS off-line method has the best reproducibility for the detection of hydrogen isotopes, while the Gasbench Ⅱ-IRMS online analytical method has poor reproducibility. The Gasbench Ⅱ-IRMS online analytical method and Dual-inlet IRMS off-line method provide better oxygen isotope composition data in precision and reproducibility than the TC/EA-IRMS method. Both international standards and national standards were used to calibrate the data obtained by TC/EA-IRMS respectively. Maximum absolute deviation of hydrogen isotope composition data was 1.13‰, and oxygen isotope composition data is 0.27‰. With a different water sample analysis, the Gasbench Ⅱ-IRMS online analytical method performed best for the oxygen isotope composition analysis and TC/EA-IRMS method for the hydrogen isotope composition analysis. The results differed with different calibration standards.