Abstract: The application of best estimate plus the uncertainty (BEPU) analysis method becomes trend in the nuclear power plant accident analysis and safety review. The procedure of the statistical BEPU method based on input parameters’ propagation was summarized and the key steps were analyzed. The evaluation process can be divided into five major steps: Defining the target parameter(s), identifying important input parameters and their probability distribution, sampling, model analysis and target parameter analysis. It’s believed that phenomenon identification and ranking table (PIRT) is a suitable method to identify the important input parameters. The distribution of input parameters is usually obtained from the experimental data or expert judgment. The parametric or nonparametric sampling method can be used to determine the required sampling number, and the later greatly decreases sampling number. Its calculation model should be verified sufficiently to demonstrate its applicability. The statistical results of objective parameter provide uncertainty range and the sensitivity of the input parameters.