Natural　gas　hydrate　(NGH)　is　a　clean　energy　source　with　huge　resource　volumes.　How　to　exploit　NGH　efficiently,　economically,　and　safely　has　recently　generated　interest.　CO2　hydrates　can　form　under　milder　conditions　than　NGH,　so　injecting　CO2　to　assist　NGH　exploitation　has　been　extensively　researched.　Based　on　this,　this　review　discussed　how　injecting　CO2　enhances　marine　NGH　exploitation　and　presented　a　win-win　strategy　for　clean　energy　access　and　carbon　storage.　We　first　demonstrated　that　CO2　hydrates　can　form　in　marine　NGH　depositional　environments,　and　then　summarized　three　modes　of　CO2　injection,　and　innovatively　studied　the　applicability　of　NGH　stimulation　principles　to　hydrate-based　CO2　sequestration.　The　review　mainly　revealed　that　(i)　the　phase　transformation　of　CO2　in　NGH　reservoirs　is　affected　by　temperature,　pressure,　minerals,　and　salinity,　and　liquid　CO2　can　form　mixed　hydrates　with　residual　CH4　to　achieve　long-term　stable　storage.　(ii)　CO2　replacement,　CO2　hydrate　cap,　and　carbon　sequestration　in　depleted　reservoirs　are　advanced　coupling　modes.　Considering　the　accumulation　characteristics　of　most　marine　reservoirs,　it　may　be　more　reliable　to　choose　injecting　CO2　or　CO2/　N2　after　exploitation.　(iii)　The　principle　of　NGH　enhancement　measures　is　beneficial　to　CO2　hydrate　formation:　Low　temperature　caused　by　depressurization　can　increase　the　driving　force　of　CO2　hydrate　formation;　Expanding　the　contact　area　between　wellbores　and　reservoirs　allows　more　CO2　injecting;　Improving　the　reservoir　permeability　is　conducive　to　heat　and　mass　transfer.　Multi-gas　source　extraction　can　enrich　the　storage　space　of　CO2.　These　key　findings　can　help　us　understand　these　coupling　modes　more　deeply.