Marine ecological capital is defined as marine ecological resources which have direct or indirect contribution to social and economic production and provide benefits for human. Marine ecological capital value refers to monetized benefits to humans gained from marine ecological resources. Assessment of marine ecological capital value can indicate the importance of the marine ecosystem and also help us to quantitatively identify its contribution to local socio-economic development. Considering the characteristics of marine ecosystems, the constituents of marine ecological capital value were identified based on the theories of both natural capital and ecosystem services. Marine ecological capital value consists of the stock value of marine ecological capital and the marine ecosystem service value, the benefits from product and service flows provided by marine ecological resources. The existing value of marine ecological resources includes two elements: the standing stock value of marine living resources and their habitat resources. Here habitat consists of sea water and surface seabed resources. Marine ecosystem service value includes four elements: provisioning service value, regulating service value, cultural service value, and supporting service value. Considering the real utilization characteristics of China′s coastal ecosystem, a set of assessment indicators for each constituent was developed. For marine living resources assessment, fish, shellfish, crustaceans, cephalopods, macro-algae and other highly-value biological resources should be considered. However, this study has not found there are any acceptable and practical indicators to measure the ecological value of the standing stock of habitat resources. For provisioning services, mariculture production, fishing production and oxygen production should be assessed. For regulating services, climate regulation and waste treatment should be evaluated. Cultural services should be measured by recreation and scientific services. The valuation of supporting services should include an assessment of services for maintaining species and ecosystem diversity. In addition, this article compared marine ecological capital value with marine natural capital value and marine resource value. The article also discussed the relationship between marine ecological capital stock and marine ecosystem service flow, as well as the position of marine ecosystem service value in marine ecological capital value. The paper also addressed the relationship between mass and value assessment of marine ecological capital.