Presently, there are no systematic researches on estimating loss-of-life caused by dam break in China. On the basis of the combination of fuzzy matter-element and exponential smoothing algorithm, a new estimation method is put forward in the paper. The principle and procedure on estimating the loss-of-life based on the combination of fuzzy matter-element and exponential smoothing algorithm are analyzed in detail. According to the historical data of broken dams in China and by using leaving one out cross validation, the result shows accuracy of the estimation method.