Abstract: In inertial confinement fusion(ICF), the hollow glass microsphere(HGM) is the first pellet, and the measurement of gas gross, constituent and density in HGM is very important. In this paper, the measurement methods of the D₂ gross in HGM by isotopic dilution mass spectrometry(IDMS) are described. The mixture of D₂ and H₂ was firstly prepared with H₂ as the spike and active carbon as the adsorbent. Then the isotope abundance of the mixture was measured by mass spectrometer. And the mole number of D₂ in HGM was calculated with the gas state of equation. The results show that the trace D₂ can be measured by IDMS, and the lower measurement limit is 10^-8 mol. The relative standard deviation of the measurement is less than 5%(n=4 or 3, calculated by range method), meeting the requirement.