The invention relates to an intelligent deduction method for a large-area power failure event based on a Bayesian network, which comprises the steps of summarizing the general evolution process of power security emergencies through typical large-area power failure cases; analyzing multiple paths of large-area power failure event evolution by surrounding three elements such as the scenario state, processing method and processing target, selecting key scenarios, and constructing a scenario network of event development; calculating the conditional probability of hopping between network nodes by combining historical cases and expert opinions; and building a Bayesian network of the large-area power failure event by means of simulation, and realizing the multi-path and multi-result deduction. The intelligent deduction method effectively solves the problems of uncertainty and multiple paths of scenario deduction of the typical power security emergencies, can visually reflect the effect of emergency measures, and facilitates the emergency personnel to timely adjust disposal measures and continuously improve the emergency level. The intelligent deduction method has important significance for analyzing the evolution mechanism of emergencies.