Abstract: The cryogenic preparation gas chromatography method for the use of hydro-gen isotope separation was introduced in the paper. The procedures for preparation andoperation of Al_2O_3, chromatographic column were investigated, and the separation effectsof Al_2O_3, separation column were discussed. The experiment results show that the purityof deuterium reaches above 99. 9% after the separation and purification for H--D mixedgas. This system possesses with some advantages, such as simple structure, low opera-tion cost, less investment and it not only can be used for the separation of hydrogen anddeuterium, but also used for the separation of deuterium and tritium. It is promised forengineering applications, particularly in some laboratories and departments where asmall amount of high purity species of hydrogen isotope is required.