The　high　precipitation　around　Southeast　Asia　results　in　abundant　freshwater　outflow,　which　transports　terrestrial　dissolved　and　particulate　material　to　the　world＇s　largest　marginal　sea,　namely,　the　South　China　Sea　(SCS).　To　estimate　the　riverine　carbon　flux　to　the　SCS,　carbonate　data　from　42　rivers　were　collected.　These　results,　combined　with　literature　data　for　13　rivers,　indicate　that　the　concentrations　of　dissolved　inorganic　carbon　(DIC)　are　positively　correlated　with　the　cation　exchange　capacity　and　the　bulk　density,　except　for　the　Low　Discharge　category.　The　highest　DIC　concentration　and　flux　are　in　the　Low　and　Medium　Discharge　categories.　Negative　correlations　exist　between　dissolved　organic　carbon　(DOC)　concentrations　and　the　base　saturation　in　the　Low　and　High　Discharge　categories　and　between　DOC　and　bulk　density　in　the　Low　and　Medium　Discharge　categories.　However,　the　correlation　between　the　DOC　concentration　and　the　organic　carbon　content　in　the　soil　is　only　significant　in　the　Medium　Discharge　category.　Once　the　negative　exponential　relationships　between　the　particulate　inorganic　carbon　(PIC)　or　the　particulate　organic　carbon　(POC)　and　the　total　suspended　matter　are　determined,　these　can　be　used　to　estimate　the　PIC　and　POC　carbon　fluxes.　Of　the　annual　riverine　carbon　flux,　83.0 ± 8.1 Tg C,　40.14 ± 6.11 Tg　is　DIC,　25.03 ± 4.54 Tg　is　DOC,　1.83 ± 0.35 Tg　is　PIC,　and　16.03 ± 2.87 Tg　is　POC.　The　total　discharge　amounts　to　6.2–10.3%　of　the　global　riverine　discharge　for　a　sea　covering　only　1%　of　the　world＇s　ocean　surface　area　and　for　watersheds　covering　only　2.2%　of　the　global　land　mass.　©2017.　American　Geophysical　Union.　All　Rights　Reserved.