The mechanism of cascading failure blackout of modern power system is expounded. According to different starting points of modelling, the research on cascading failure blackout is divided into two branches: one of the branch is based on power flow calculation and stability analysis, in which modelling analysis and events mode search strategy based on complex system theory are presented; the other is based on the research of power system network topology, which mainly focuses on the small-world network model and the scale-free network model. Finally, some possible key technical problems to be solved for the research on cascading failure blackout of power system are pointed out.