The modeling of cascading failures in power systems can be used to analyze the dynamic behaviors and propagation mechanisms of the complex cascading failures in power grids. This paper summarizes the current models of cascading failures in power grids and the research development situations in recent years from the perspective of complex system theory. The modeling processes of Holme-Kim model， Motter-Lai model， Crucitti-Latora model， weighted-network model， time-varying model and their applications in power systems are introduced in details. Finally， the future research directions of smart grid modeling using complex system theory are proposed based on the discussion of these models limitations.