Abstract: As a high-energy-consumption scenario, the internal IT equipment, cooling systems, and auxiliary facilities of big data centers generally have DC characteristics. However, the traditional AC power supply mode suffers from prominent efficiency losses and reliability issues due to multi-stage power conversion. Based on the analysis of the typical energy consumption structure of big data centers, this paper conducts a study on the AC-DC hybrid power supply mode. First, it analyzes the power consumption characteristics and DC proportion of the main loads in big data centers, clarifying the technical feasibility of direct DC power supply. Then, it constructs an AC-DC hybrid power supply architecture with a multi-terminal ring structure as the core, realizing the flexible access and coordinated operation of DC power sources and loads. By comparing with the traditional AC power supply mode, a comprehensive analysis is carried out from the aspects of energy efficiency improvement, reliability enhancement, and economy. This study can provide theoretical basis and technical reference for the design and transformation of power supply and distribution systems in big data centers oriented to the goals of greenness and low carbon.