Abstract: The Mass Spectrometric Measurement of Helium Isotope in WaterSun Mingliang(The State Key Laboratory of Gas-Geochemistry,Lanzhou Institute of Geology,Chinese Academy of Sciences,Lanzhou 730000,China)Received Abstract:This is a studying report about helium concentration in water and about the mass spectrometric analysis technlogy of helium isotopes.the special glass bottles were used to sample the water,and the rate of vacuum degassing is higher than 98%,the He and Ne purified out were measured in mass spectrometer.Taking the He of atmosphere as standard sample and using the method of mass spectrometic peak height ratio with ABA pattern,the concentration and isotopes of helium in the samples of distilled water,spring water,shallow layer sea water of West Pacific Ocean and so on were measured.This technology has been successfully applied to the reasearch about the distribution of helium isotopes in the shallow layer sea water of West Pacific Ocean.Keywords:water,helium isotope,mass spectrmetric measurement