The distribution characteristics of tritium in natural water in the area of Qinghai Lake is presented. The content of tritium in natural water averages 342±33T.U.
but the average content in river and well water is 316±30 T.U. and that in lake water is 363土34 T.U.. The content of tritium in river water changes with season. The distribution of tritium in surface water is homogenous while the vertical distribution changes with the temperature of water.