The reasonable determination of the access point of the large power supply connected to the power grid is of great significance to the hierarchical partition and the rationalization of the power grid structure. Therefore, in this paper, the method of evaluating the rationality of the access point of the large power supply connected to the power grid by using the improved gray correlation analysis method based on the comprehensive weight is studied. The short circuit current, the power flow distribution, the network loss, the stability, and the N-1 fault check result are selected as the comprehensive evaluation index. And the overall short-circuit current level, the trend of entropy, network loss, V-Q sensitivity, and the number of N-1 fault load line are used to describe the above evaluation index quantitatively. In order to avoid the limitation of the single weighting method, firstly, the combined weighting method to determine the comprehensive weight of each index is used, and then the improved gray correlation analysis method based on the comprehensive weights is applied to evaluate the scheme of the access point of the large power supply connected to the power grid comprehensively. Finally, the PSD power system analysis software is adopted to carry out the simulation. The effectiveness and feasibility of the proposed method are verified by the simulation example.