【Objective】 The availability of soil phosphorus (P) usually limits the productivity of fluvo-aquic soil. In order to provide a scientific basis for improving P use efficiency and rational fertilization in fluvo-aquic soils, the adsorption characteristics of P and its relationship with soil properties under long-term fertilization were studied. 【Method】 We selected seven treatments: no fertilizer (CK), no P fertilizer (NK), no potassium fertilizer (NP), no nitrogen fertilizer (PK), mineral fertilizer NPK (NPK), half compost plus half mineral fertilizer NPK (1/2OM) and compost alone (OM) in a long-term fertilization experiment at Fengqiu, to determine soil properties and P adsorption capacity. The Langmuir and Freundlich equations were used to fit the isothermal adsorption curves. Furthermore, the maximum adsorption capacity (Q_m), adsorption constant (K), maximum buffer capacity (MBC), P adsorption saturation (DPS), Freundlich adsorption constant (a) and adsorption index (b) were calculated. Correlation analysis and redundancy analysis (RDA) were used to explore the vital factors affecting the soil P adsorption characteristics.【Result】 The results showed that P adsorption in fluvo-aquic soil fitted both the Langmuir (R²≥0.80) and Freundlich (R²≥0.89) isotherms. With the increase of P concentration in the equilibrium solution, P adsorption capacity rapidly increased at first and then slowly afterwards. Compared with CK and NK, Q_m and MBC of NP, PK and NPK increased by 15.62%～23.60% and 2.94%～23.46%, respectively, however, K and MBC of 1/2OM and OM reduced by 39.60%～49.57% and 36.09%～56.15%, respectively. Correlation analysis and RDA results showed that organic matter (SOM), pH, free Al oxides (Al_d) and C/P were the main factors affecting P adsorption characteristics of fluvo-aquic soil. In addition, the DPS of 1/2OM was 30.92% lower than that of OM.【Conclusion】 Long-term combined NPK fertilizer with compost can increase the content of SOM, reduce P adsorption capacity and reduce the risk of P loss compared with OM.