A correlation assessment method of power grid cascading failure accident chains comprises the steps that (1) a system is initialized to be in a normal operation working condition; (2) initial failures happen to circuits with equal probability, circuit initial failures are circuit three-phase permanent short-circuit failures, relay protecting action failure removing in a set time is carried out, and for direct-current circuit, the initial failures are direct-current circuit single-pole locking failures; (3) based on the previous circuit failure situations, transient stability analysis is carried out on an electric system, if system transient is unstable, the step (7) is carried out; and if system transient is stable, the step (4) is carried out; and other steps are carried out. According to the method, on the basis that the correlation between cascading failures can be considered, system transient stability failures can be subjected to effective searching, searching correlation probability is given, system states and topology are considered, meanwhile, high computing efficiency is achieved, and certain guiding effect is achieved on cascading failure searching and accident chain recognition.