In order to study the variation of phosphorus forms, sorption capacity and the potential releasing risks, the phosphorus forms and sorption index were analyzed in the barren wetland and Spartina alterniflora invasion wetland of Min River estuary. The results indicated that inorganic phosphorus (IP) was the main form of soil phosphorus, which accounted for 61.40% and 61.01% of total phosphorus (TP) in soils of the barren wetland and Spartina alterniflora invasion wetland, respectively. The concentrations of TP, IP, iron and aluminum-bound phosphorus (Fe/A1-P) and calcium-bound phosphorus (Ca-P) were all significantly higher than those of the barren wetland, and the increase percentage were 12.58%, 9.49%, 11.11% and 5.32% in turn, while the organic phosphorus (Org P) had no significant change. Furthermore, Spartina alterniflora invasion had different impacts on the amorphous phosphorus (Pox), iron (Feox), aluminum (Alox), the phosphorus adsorption index (PSI) and the degree of phosphorus saturation (DPS), and the Feox and DPS were not significantly changed. However, the Pox and PSI were increased significantly, while the Alox was significantly decreased. The potential releasing risk (ERI) of the barren wetland was 12.69, which was belonged to middle risk, nevertheless, the ERI of the Spartina alterniflora invasion wetland was reduced to 9.98, which was belonged to low risk, indicating that Spartina alterniflora invasion could lower the releasing risk of soil phosphorus in wetland.