The invention relates to a multi-evaluation-index-based regional grid key line identification method. The method comprises the following steps: inputting power system parameters; calculating various evaluation index values of a line; after standardized processing, calculating weights of all indexes under subjective and objective weighting methods; establishing an optimal combination weight model based on a moment estimation theory to determine a comprehensive weight of the indexes; and according to a radar map, calculating a comprehensive evaluation result of the line and identifying a key line in the grid. According to the invention, the importance of the line is analyzed by using multiple indexes; and thus compared with the single evaluation index, the multiple indexes enable the resultto be comprehensive and reasonable. The index weights are determined by using the optimal combination weight model, so that advantages of the subjective and objective weighting methods are both considered. On the basis of the radar map method, the line is evaluated comprehensively, so that the influences on the key line identification result by various factors are reflected vividly and visually and thus the decision maker is assisted in making the correct strategy. With the method provided by the invention, the key line of the grid is identified well and the evaluation result conforms to the actual operation condition of the grid.