Abstract: The probability safety assessment (PSA) method of nuclear power plant (NPP) severe accident consequence is to apply probability theory to analyze radioactive consequences of nuclear power plant and assess quantitatively the public health effects around nuclear power plants. Taking a domestic PWR NPP as a reference site, an appropriate off-site consequence analysis model was established. The stratified sampling method was used for meteorological sampling within a year meteorological data, and the radioactive source term and release characteristics data were from level two PSA. Using nuclear power plant accident consequence assessment code to calculate the off-site severe accident consequences, the results obtained by probability method were assessed. The off-site individual dose of each accident and accident spectrum can be expressed as CCDF curve and total frequency-dose curves by means of calculation, and according to the probability assessment method, the conditional probability of individual doses exceeding the specified dose can be obtained. Also this method can be used to quantify the most severe accident sequences described in the safety standards for determining the plume emergency planning zone.