With the micro-grid charging station connecting into distribution system, it exists power source in radiated distribution network which cannot be equivalent to a passive load point in traditional transmission system risk assessment of distribution network. A risk assessment method for transmission system considering micro-grid charging station is proposed to analyze this effect. First of all, this paper introduces theoretical basis of risk assessment, then emphatically analyzes probability model of micro-grid charging station, including output probabilistic model of distributed generation and charging load probabilistic model of Electric Vehicles (EV). The expected load curtailment influenced by distribution network is applied to replace absolute load curtailment. Finally, the effectiveness of the proposed method is verified by using a testing system, the influence on risk index of transmission network by the proportions of distributed generation capacity and reverse power transmission network in micro-grid charging station is analyzed. The analysis results show that micro-grid charging station connected into distribution network can effectively reduce risk level of transmission system.