Carbon participates in the global carbon cycle in many forms in the ocean, in which total organic carbon (TOC) buried in marine sediments plays a crucial role in the worldwide carbon cycle. As a transition zone with high physical energy and productivity worldwide, the marginal sea stores more than 80% of the organic carbon in the global ocean. Covering a total area of about 4.7 million square kilometers, China's marginal sea has significant carbon storage capacity and prospects. With the implementation of China's “Double Carbon” program, the study related to marine carbon storage has become a hot research topic in recent years. The review summarizes the distribution characteristics of organic carbon distribution, main sources, and influencing factors, as well as the potential of carbon storage in the marginal sea sediments of China. In addition, the review also provides an outlook on the possible future research directions, aiming at providing certain references for the related work on marine carbon storage and carbon cycle in China's marginal sea.