Abstract：Yemaquan district，one of the important candidate sites for China¢s high-level radioactive waste repository，is located in the Beishan area，Gansu Province，Northwest China. The granite is widely distributed in this district and it will be a good host rock for a high-level radioactive waste disposal repository. In order to understand the hydrogeological conditions and to evaluate if the district is a suitable/unsuitable site for a repository，the isotopic hydrogeological investigation and research were carried out during last decade. According to the field investigation and the analysis of the stable isotopes of hydrogen and oxygen，it is concluded that both shallow groundwater and deep groundwater are of meteoric origin. The shallow groundwater is recharged mainly by modern 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，it is also found that the shallow groundwater system is relatively open；and the ability of water circulation is more capable than that of deep groundwater system.
