Abstract: This paper presents a model of the cyber physical power system（CPPS）cascading failures based on the improved percolation theory.In this model,the dynamic developing process of cascading failures in CPPS is divided into several stages.The physical layer power grid AC power flow analysis is incorporated in the stage corresponding to the failure propagating in the physical layer.The vulnerable indices include both topological integration,the increment of cyber layer delay and physical layer operation status.Simulations of cascading failures in the CPPS with various interdependence interface and node attack strategies show that the topological centrality interface strategy exhibits better robustness,compared with the centralized control center,the distributed control center strategy in the physical layer can improve the time-delay situation in the cyber layer during the cascading failures.Meanwhile,the topological centrality based node deliberate attack strategy can cause more rapidly developing cascading failures and heavier damages to the CPPS.