Marine science and technology policies play a crucial role in promoting the high-quality development of the marine economy and accelerating the building of a maritime power.This study focuses on China’s marine science and technology policy system， taking 229 relevant policy documents issued by central and local governments between 1991 and 2025 as its subject matter.It constructs a three-dimensional analytical framework comprising ‘policy instruments—policy objectives—development stages’ and employs a combination of bibliometric and content analysis methods to conduct quantitative research.The results indicate that China’s marine science and technology policies have undergone three stages： “Inception and Establishment”， “Deepening and Expansion”， and “High-Dimensional Explosion”， exhibiting distinct phased evolution and explosive growth in volume during the later stages; the structure of policy instruments is imbalanced， with an excessively high proportion of supporting service-oriented instruments and insufficient use of incentive-based instruments， reflecting a tendency to “prioritise service-oriented guidance over incentive-driven stimulation”; policy objectives are unevenly prioritised， with high attention given to the high-quality development of the marine industry and independent scientific and technological innovation， whilst support for objectives such as marine ecological civilisation， open cooperation and modernised governance remains relatively weak; a three-dimensional cross-analysis further reveals that policy instruments lack sufficient alignment between objectives and across stages， with coverage gaps existing in certain key areas.Consequently， future efforts should concentrate on optimising the structure of the policy toolkit and increasing the use of incentive-based tools; strengthening targeted support for weaker policy objectives to enhance the synergy of the objective framework; and dynamically adjusting policy priorities in line with the characteristics of different development stages， whilst strengthening top-level strategic design and end-to-end management， in order to systematically enhance the overall effectiveness and sustainability of China’s marine science and technology policies.