Growing evidence suggests that land use has widespread effects on soil phosphorus (P) cycling, which can contribute to plant growth and environmental impacts. P pool and P behavior characteristics have identified as potential indicators of soil nutrient cycling and functions. In this study, we investigated effects of different land-use types (farmland and ecological buffer zone) on soil P fractions (i.e., labile P, moderately labile P, organic P, apatite P, and residual P) and soil P sorption-release characteristics at three sampling sites in the eutrophic aquatic-terrestrial ecotone of Dianchi Lake, China. In addition, we also identified key soil physicochemical properties that were significantly related to soil P fractions and sorption-release characteristics. Different land use induced changes in soil P fractions and P stocks. Organic P pool showed a significant difference between FL and BZ in all sites and other P pools displayed the site-specific responses. Soils in buffer zone have higher P buffer capacity (higher maximum sorption capacity and lower degree of P saturation) in comparison with farmland. Moreover, soil buffer capacity was significantly correlated with soil labile P. These results suggest buffer zone in lakeside may act as sink of P in reducing soil P loss. However, higher labile P and very low C: Po ratios (<100) in all soil samples indicate there is large amount of available P accumulated in soils and soil P loss risk in the aquatic-terrestrial ecotone is still high. Redundancy analysis results showed that the soil key physicochemical properties (soil organic carbon, total nitrogen, exchangeable Fe and Al concentration, and pH) were closely related to soil P fractions and sorption-release characteristics. Therefore, we conclude that soil P fractions (especially labile P, organic P) and key soil physicochemical indices are useful indicators for assessing the behavior of P in soils induced by different land use in the eutrophic aquatic-terrestrial ecotone of lakes.