In　order　to　scientifically　assess　the　impact　of　land　use/land　cover　changes　on　blue　carbon　pool　of　coastal　tidal　marsh,　it　is　valuable　to　determine　the　changes　of　ecosystem　carbon　stock　following　conversion　of　coastal　marsh　to　aquaculture　ponds.　In　the　Minjiang　River　estuary　zone,　we　collected　the　samples　of　the　aboveground　and　belowground　plants,　and　the　soils　(0~100cm)　from　the　Phragmites　australis,　Cyperus　malatensis　and　Spartina　alterniflora　marshes,　and　the　top　100cm　sediment　of　the　aquaculture　ponds　reclaimed　from　above　three　different　marshes.　The　organic　carbon　content　of　plants,　and　soil　/　sediment　samples　were　measured.　The　blue　carbon　storage　of　P.australis　marsh　ecosystem,　C.malaccensis　marsh　ecosystem　and　S.alterniflora　marsh　ecosystem　was　(152.85±8.88),　(151.63±6.33),　and　(155.85±10.82)Mg　C/hm2,　respectively,　and　the　sediment　carbon　storage　of　the　aquaculture　ponds　was　(112.69±4.26),　(128.24±15.81),　and　(118.59±8.26)Mg　C/hm2,　respectively.　The　blue　carbon　storage　of　P.australis　marsh　ecosystem,　C.malaccensis　marsh　ecosystem　and　S.alterniflora　marsh　ecosystem　decreased　by　26.3%,　15.4%,　and　23.9%,　respectively,　resulting　in　(145.49±33.00),　(120.66±26.49),　and　(136.76±27.61)Mg　CO2-eq/hm2　carbon　emissions.　Our　results　showed　that　conversion　of　coastal　marsh　into　aquaculture　ponds　greatly　decreased　ecosystem　carbon　storage.　We　suggested　that　ecological　restoration　of　aquaculture　pond　into　marsh　ecosystem　will　play　an　important　role　in　coastal　wetland　carbon　sequestration.　©　2022,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.