Abstract: In order to improve the phosphorus removal capacity and investigate the process of iron ore tailing in water, the iron ore tailing was modified by heating. With the aim of phosphorus removal capacity, the response surface test was designed by taking temperature, time of constant temperature and heating rate as factors value. Moreover, the phosphorus removal process and performance of iron ore tailing before and after modification were analyzed by kinetics, isotherm and thermodynamics. The results shown that the maximum removal capacity of phosphorus by modified iron ore tailings is 2.43 mg/g at 600 ℃, which was 2.46 times that unmodified. Furthermore, It was concluded that Fe₃O₄ played a major role in increasing phosphorus removal capacity combined with literature and tailing sand composition analysis. The response surface regression model was significant (P < 0.0001) and the determination coefficient R² was greater than 0.99, indicated that the regression model was reliable. The optimal modification conditions obtained from response surface test were as follows temperature 627.84 ℃, constant temperature 3.00 h, heating rate 9.82 ℃/min, which predicted maximum removal capacity of 17.43 mg/g. The removal of phosphorus by iron ore tailing before and after modification was chemisorbed on non-uniform surface. The removal process of phosphorus from water were closer to Freundlich isothermal model. Moreover, the maximum removal amount of phosphorus in Langmuir isothermal model by iron ore tailing before and after modification were estimated as 0.19 mg/g and 149.97 mg/g, respectively. Meanwhile, the removal of phosphorus by iron ore tailing was easy to occur, △H⁰>0 shown that removal process was endothermic and the removal capacity of phosphorus by iron ore tailing could be improved by increasing the temperature.