Tidal salt marshes have a high carbon accumulation rate and low CH₄ emissions, representing some of the most dense carbon sinks in the world. In addition, salt marshes are likely to capture and bury atmospheric CO₂ more quickly in the future due to climate warming and sea level rise. Therefore, the "blue carbon" in tidal salt marshes plays an important role in the global carbon cycle and in the mitigation of climate change. Unlike other wetland types, a salt marsh is subjected to periodic flooding and exposure by tides, which leads to the alternation of salt accumulation and leaching. Therefore, tidal flooding and the drying and wetting cycles induced by tides in a salt marsh have a profound impact on the carbon biogeochemical cycle and carbon balance. However, it is still not clear how carbon exchange and carbon sequestration in a salt marsh respond to tidal hydrodynamic processes and the drying and wetting cycles. Moreover, previous studies have generally considered the vertical exchange of CO₂ or CH₄ or the transverse exchange of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and particulate organic carbon (POC) in isolation to evaluate the carbon budget of tidal salt marshes, which in turn limits the accurate assessment of the carbon sequestration process. Therefore, to accurately estimate and predict the sequestration capacity of blue carbon in salt marshes, it is important to (1) analyze the effects of different stages of the tide on the key processes of carbon exchange; (2) clarify the microbial mechanism of carbon exchange in a salt marsh under tidal action; (3) explore the tidal hydrodynamic influence on the production, release, and leaching of DOC, DIC, and POC from salt marshes to the adjacent coastal water; (4) clarify the influence of tidal action on the mechanisms of carbon sequestration in a salt marsh; and (5) incorporate the tidal hydrodynamic process into the empirical models of salt marshes to accurately evaluate their carbon budget.