A micro gas chromatography was established for the quantitative analysis of hydrogen and deuterium components in fusion reactor fuel cycle system．An alumina column（4～6 m × 0.53 mm） was modified with MnCl,2, solution．Effects of concentration of modified liquid，length of column and flow rate of carrier gas on the analysis of H/D components were studied．The mixture of H,2,，HD and D,2, were separated at LN,2, cryogenic temperature（77 K）．The results indicated that the column treated with 19% MnCl,2, solution was better than that treated with 15% MnCl,2, solution for the separation of hydrogen isotopes．The longer the column length，the better the separation effect of H,2, and HD. Under the experimental conditions，H,2, and HD components could be completely separated when the column length was longer than 5 m，and the peak resolution between H,2, and HD was larger than 1.5，resulting in the effective separation of the hydrogen isotope．Furthermore，the minimum values of HETP for HD and D,2, were 0.013 cm and 0.016 cm in the experiment，respectively．As for the three hydrogen isotopes in He，there were good linear relationships for the three components in the concentrations range of 0%－10%，with their correlation coefficients not less than 0.993 and the detection limits（LODs） of 600.1，343.8，654.5 μL/L for H,2,，HD and D,2,，respectively．The peak area relative standard deviations（RSDs） were in the range of 0.34%－1.5%．The method is a rapid，accurate and applicable analysis method for hydrogen isotope，which is expected to be applied to the analysis of hydrogen isotope gases in the D/T fuel cycle system of fusion reactor．