Abstract: The West Sichuan Plateau is one of the most concentrated areas for Kaschin Beck disease. Lack of selenium is an important factor of Kaschin Beck disease, therefore, selenium content study in this area is important for its prevention. Atomic Fluorescence Spectrometry was used to analyze the contents of selenium in water samples in the Aba region, West Sichuan Plateau. Results show that the content of selenium in water is low, and the content of selenium in groundwater is obviously higher than that of surface water and spring water. The content of selenium in spring water is 0.001-0.058 μg/L, with an average value of 0.0067 μg/L. The distribution of Se is controlled by geological background, pH and Eh. The low selenium geological environment is the most important factor leading to low selenium content in spring water. The selenium content of surface water is 0.001-0.148 μg/L, with an average value of 0.0221 μg/L, and the influence factors of selenium distribution are geological background, geographical conditions and water geochemical conditions. The content of selenium in groundwater is 0.001-0.210 μg/L, with an average value of 0.0523 μg/L, and the influence factors of selenium distribution are geological background, pH and Eh, as well as the content of organic matter. This study indicates that low selenium spring water cannot provide the selenium nutrition needed by Tibetans whose main drinking water source is spring water, and is thus not suitable as a water source. The surface water resources in the Western Sichuan Plateau are abundant. However, the migration of elements in water is very strong. Therefore, it is difficult for selenium in surface water to enter the ecological chain, making the surface water unsuitable as a source of drinking water. In order to reduce the incidence of local Kaschin Beck disease, groundwater with high selenium content should be used as a source of local drinking water.