Abstract: Yamansu and Tianhu area in Xinjiang is the main preselected section of disposal repository for high level radioactive waste(HLW) in our country. In the siting and site characterization study for high level radioactive waste repository, the groundwater chemical characteristics are the one of the most important evaluation factors. From 2009 to 2013, the field hydrogeochemical investigation was carried out and more than 30 groundwater samples were collected. According to the measurement data, the paper discussed the groundwater chemical features in Yamansu and Tianhu preselected section for China’s high level radioactive waste repository. The main conclusion is that: the groundwater in the study area is mainly saline water with high dissolved solids, 7.69-9.64 pH value, 11.8-24.0 ℃, 542.7-413375.5 mg/L total dissolved solids and Cl•SO₄—Na, SO₄•Cl—Na and Cl—Na chemical types. The hydrogeochemical features show that lixiviation and evaporation are the basic pattern forming the groundwater chemistry in the section.