Gasbench-Ⅱ continuous flow isotope ratio mass spectrometer (CF-IRMS) online analysis has been used to analyze δD, δ18O and δ13CDIC in water sample. In order to analyze the accuracy and precision of the Gasbench Ⅱ-IRMS detection method for the δD, δ18O and δ13CDIC. By comparing The Third institute Of Oceanography State Oceanic Administration, Hohai university, Nanjing Institute of Geology and Mineral Resources , Chengdu university of technology, The Institute of Hydrogeology and Environmental Geology, Institute of Mineral Resources,Chinese Academy of Geological Sciences and Institute of Karst Geology using online continuous flow Gasbench Ⅱ-IRMS analysis methods to analyze water samples. Using CO2-H2O balance method and H2 - H2O equilibrium methods to analyze δD and δ18O in water sample(Sample ID: YHS, YYNS and YXZS), phosphoric acid method to analyze δ13CDIC in water sample(Sample ID: HDIC, HBLS, KSTD,HNF,HHSY). The δD, δ18O and δ13CDIC test data show that for continuous flow Gasbench Ⅱ-IRMS get good results, accuracy and precision are basically identical. The δD precision less than 1.05 ‰, the δ18O precision less than 0.15 ‰, the δ13CDIC precision less than 0.12 ‰. In this paper, we study for the GasBenchⅡ-IRMS detection in testing technology selection provides a certain reference, guarantee the δD, δ18O and δ13CDIC reliability and accuracy of the result.