Photosynthetic　carbon　is　an　integral　part　of　carbon　cycle　in　plant-soil　system,　also　is　an　important　source　of　soil　organic　carbon.　In　this　study,　13C　labeling　was　used　for　exploring　allocation　of　photosynthate-13C　in　Phragmites　australis　-soil　system　undergoing　the　salt　marsh　restoration　project　by　freshwater　pumping　in　Yellow　River　Estuary　(YRE),　China.　Samples　were　collected　from　T0　(before　labeling)　to　90　days　after　labeling　(T4),　in　natural　salt　marsh,　5-,　10-　and　15-year　freshwater　pumping　areas,　respectively.　The　photosynthate-13C　contents　of　soil　were　gradually　decreased　to　0　mg/g　at　T4　in　most　areas,　while　it　was　2.21　mg/g　in　15-year　pumping　area,　higher　than　other　areas　at　the　last　sampling　time　(T4).　And　the　allocation　of　photosynthate-13C　in　soil　was　increased　from　3.58%　at　T2　to　44.46%　at　T3　in　natural　salt　marsh,　while　no　significant　change　was　found　in　other　areas　from　T2　to　T3,　followed　by　the　significantly　higher　photosynthate-13C　proportion　in　soils　of　15-year　pumping　area　at　T4.　EC　(R2　=　0.5972)　and　small　macro-aggregates　proportion　of　soil　(R2　=　0.4829)　had　positive　correlations　with　Δ　photosynthate-13C　(the　value　of　photosynthate-13C　in　underground　part　minus　that　in　soil);　silt　and　clay　fractions　proportion　of　soil　(R2　=　0.7044)　had　negative　correlation　with　Δ　photosynthate-13C.　Distribution　and　transportation　of　photosynthetic　carbon　in　the　underground　were　affected　by　soil　physical　and　chemical　properties.　©　2019　Elsevier　B.V.