Abstract: Vehicle-to-Grid (V2G) plays a crucial role in enhancing power-system flexibility and facilitating renewable energy integration. To identify the priorities and weaknesses of V2G support policies, a three-dimensional “Structure–Theme–Instrument” analytical framework was developed and a quantitative analysis of 102 national and local policy documents was conducted. Compared with traditional single-dimension text analysis, this framework reveals the internal linkages among policy structure, themes and instruments. The results are as follows. First, China’s V2G support policies have entered a stage of comprehensive promotion; the number of policy issuances peaked at 42 in 2023. At the national level, opinions and notices dominate, while at the local level implementation plans and opinions are predominant, accounting for 85.8% and 65.5% respectively. Second, seven national and six local policy themes are identified: national policies emphasize technical standards and pilot projects, whereas local policies focus on charging infrastructure, economic incentives and user participation. Third, there is a clear imbalance in policy-instrument configuration at both levels: environmental and supply-side instruments dominate, whereas demand-side instruments are underused, and user incentives as well as business-model support remain weak. It is therefore recommended to strengthen cross-departmental coordination and refine user incentive mechanisms, so as to improve V2G support policies in a tiered and differentiated manner and promote the further application and development of V2G technologies.