Abstract: Smart grid is a typical cyber-physical system（CPS）, in which the disturbance on cyber part may result in the operation risks on physical systems. In order to perform system assessment and contingency analysis for the cyber-physical power grid, we first reviewed the significance and necessity of the CPS assessment for the power system, and proposed an analytic cyber-physical modeling architecture to describe the couple relationship of cyber and physical systems adopting graph theory, set theory and matrix theory afterwards. In this model, the HCS cyber network can be abstracted to a directed graph consisting of data nodes and directed branches. This model supports hybrid computing of the system information-energy flow with matrix transformation and operations, which has a higher computational efficacy while ensure some accuracy compared with simulation-based approaches. At last, we also explored the outlook of the future cyber-physical security assessment for the power system.