Abuse of fossil energy resources results in the excessive discharge of greenhouse gases,especially CO_2,enhancing the trend of global climate warming. Carbon sequestration is an important method to lower the increasing rate of CO_2 concentration in the atmosphere. Marine carbon sequestration is a novel idea for reducing CO_2 emission,and its reservoir mainly includes seawater and submarine sediment,which not only possess a great potential capacity of carbon sequestration, but also have high safety in relation to continental reservoirs. In this paper, we expounded the technique principle and mechanisms of marine carbon sequestration,potential capacity and time duration of marine carbon sequestration, main factors influencing marine carbon sequestration, CO_2 injection technique,impacts on marine biota from over emission of CO_2 and technique monitoring the leakage of CO_2. Finally,a prospect of marine carbon sequestration was proposed, and its hot topics were accordingly pointed out.