Phosphate adsorption kinetics and isotherms on sediments under different vegetation types in Hangzhou Bay wetland were studied, and the influences of the sediment physicochemical properties on phosphorus sorption characteristics were analyzed. The results showed that there are three stages during sediment adsorption process with rapid adsorption (0–1 h), slow adsorption (1–16 h) and balance (16–72 h). The trend was not affected significantly by different plants. Indexes fitted from improved Langmuir model showed that sediment Qmax was between 154.5–436.2 mg/kg, and was significantly higher in sediment with plant growth than that of bare mudflat. Sediment NAP was between 1.853–4.777 mg/kg, indicating a low native adsorbed exchangeable phosphorus. NAP trends between different types of sediments were similar to that of Qmax values. Sediments EPC0 under different vegetation types were lower than soluble reactive phosphorus concentration in the overlying water. So the sediment acts as the “sink” of phosphorus from tidal water. The variation of EPC0 between different sediments was minor. Correlation analysis showed that the sediment Qmax and NAP in Hangzhou Bay wetland were affected by organic matter, particle composition and total inorganic phosphorus concentration, and Qmax was also affected by the electrical conductivity value. However, there are no significant correlations between sediments EPC0 and physicochemical properties. In conclusion of that, plants can affect the physical and chemical parameters of sediments, thus can affect the adsorption kinetics and isotherms of phosphorus.