Marine biodiversity is the indispensible part of global biodiversity. Although China is abundant with marine biological resources, its biodiversity is seriously threatened. Recently, the number of endangered marine species on record has reached 556. The status quo and characteristics of the endangered marine species in China were summarized, the cause why marine organisms decrease or are even endangered was analyzed, and the protection measures of marine endangered species and marine diversity were expounded in China. A series of protection measures and suggestions was then put forward for marine biodiversity conservation and sustainable development of the marine environment.