[en] Knowledge of the hydrogeological conditions is of paramount importance in the safety assessment of a waste repository since any radioactive materials released from the repository will be transported to the human environment or biosphere more or less exclusively by groundwater. Yemaquan district, the one of the important potential site for China's high level radioactive waste repository, is located in the Beishan area, Gansu Province, northwestern China. The district is in the rocky Gobi Desert region, with dry climate, little precipitation, few or no inhabitants, no prospects of economic development and far from a large population center (130 km away from Jiayuguan city). The granite is widely distributed in this district and can be good host rock for a high level radioactive waste disposal repository. In order to understand the hydrogeological conditions and evaluate if the district is or is not a suitable site for a repository, the isotopic hydrogeological investigation and research was carried out during last few years. According to the field investigation and the analysis of the stable Isotopes of hydrogen and oxygen, we can conclude that both shallow groundwater and deep groundwater are of meteoric origin. The shallow groundwater is recharged mainly by modem and local precipitation, and the deep groundwater may be originated from regional precipitation at higher elevation. In addition, from the tritium data of groundwater in the district, we can also understand that the shallow groundwater system is relatively open and the ability of water circulation is more capable than deep groundwater system. (authors)