Abstract: A reliability evaluation model of Cyber-Physical System (CPS) for distribution network based on generalized stochastic Petri nets (GSPN) is proposed. Firstly, considering the dynamic control relationship of CPS of distribution network, based on the basic principle of generalized stochastic Petri nets, the Petri net model of CPS of distribution network is constructed. Then, combined with the maximum flow theory, the number of tokens in each stage after the fault is judged, and the corresponding reliability index is calculated. The evaluation method based on Petri net can intuitively describe the system topology and component state changes, and infer the failure consequences through dynamic equations, avoiding the traversal process of failure consequences analysis and improving the evaluation efficiency. Finally, taking the IEEE-RBTS BUS6 power distribution system as an example, the simulation test is carried out to verify the validity of the proposed model.