With increasing attention being paid to the national strategy of "west-to-east power transmission" and the continuous improvement of the wide-ranging and optimal allocation of clean energy, it will become a common problem for multi-DC to replace the conventional power supply. This will bring about the terminal hollowing of the power grid. This paper mainly takes the Henan power grid and central China power grid as examples to analyze the main characteristics of power flow evacuation, voltage stability, power angle stability, small disturbance stability and multi-feed short-circuit ratio. As the results show, after the above projects are put into operation, the power supply capacity of the receiving grid and the flexibility of the mutual aid between different areas can be greatly improved. However, there may be some problems such as the imbalance of power flow evacuation, the decrease of transient voltage, power angle and system dynamic stability, and the decrease of the effective short-circuit ratio of the DC multi-feed across the region. In view of the above problems, this paper puts forward some suggestions on how to arrange the operation mode reasonably and strengthen the synchronization between the AC grid and the DC project, and the effectiveness of the proposal is also verified. This study could be referred to for power grid planning, power grid operation and other similar HVDC transmission projects. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 521700190010) “Study and Demonstration of Application Key Technologies of Electrochemical Energy Storage Power Plant Clusters in UHV AC/DC Hybrid Receiving-end Power Grid”.