Abstract: With the development of information technology, the means of network attacks are increasing and becoming stronger, and it is impossible to achieve complete defense against network attacks in a true sense.Therefore, it is particularly important to evaluate the system vulnerability under network attacks.This paper studies the network topology and cascading failure process of distribution network information physical systems in network attack scenarios.A cascading failure model and vulnerability evaluation index of the cyber physical system for distribution network have been established, taking into account the overload status of information nodes and the emergency recovery process.The simulation based on the improved IEEE 118 node and Barabási-Albertmodel scale-free network verifies that the model can better describe the actual situation.Meanwhile, the impact of network performance parameters on the vulnerability of the cyber physical system for distribution network is calculated and analyzed, providing reference for optimizing system defense strategies.