Abstract: Probable maximum rainfall (PMP) is one of the important parameters for flood safety and drainage system design of nuclear power plants. Based on the analysis of rainstorm characteristics and weather cause in the coastal nuclear power plant, the 24 h PMP of the plant site was calculated by using the local rainstorm amplification method (vapor amplification method and vapor efficiency amplification method) and the displacement rainstorm amplification method. After checking the rationality of the calculation method for the analysis, the comparison of calculation results with the measured data and similar nuclear plant projects, the result has been recommended as the PMP of the project. Through the rationality check of the calculation scheme, and comparison with the possible maximum 24 h rainfall contour map of Shandong Province and the 24 h PMP results of other nuclear power plant projects, the 24 h PMP of the site was determined to be 1 100 mm. The research results can provide reference for PMP research in similar watersheds in China.