A vulnerability assessment method for micro-grid operation is proposed in this paper based on micro-grid topological structure and operation state.Firstly, the concept of micro-grid vulnerability is defined under the isolated island operation state.Secondly, real-time probabilistic model is established for vulnerability assessment after analyzing influencing factors of vulnerability and risk consequence generous character function based on risk theory is established.Finally, the proposed model is verified on a typical case.The simulation results show that the weak part can be found timely, which provides the reference for self-healing decision.