Abstract: The main reason why the flood water take place on Yerqiang River is that the river valley was blocked by glaciers. In the present paper, the reserve volume of glacier block lake in history is calculated with accuracy analysis on the base of the detail data, and the maximum reserve volume in the future is predicted. A group of models for reserve volume and flood amount on the down stream so as to calculate reserve volume and flood amount and to determine that which one of river valleys is blocked. Finally, the maximum flood water, which possibly appears in the future, is calculated 688.40 m³/s .