P adsorption on pyrrhotite obeyed Langmuir adsorption isotherm and the second-order kinetics. The overall adsorption mechanism was chemisorption, by which Fesingle bondS bonds on the surface of pyrrhotite particles would be broken and a new Fesingle bondOsingle bondP structure would be formed. The adsorption capacity of pyrrhotite was up to 0.79–1.15 mg/g at 11.3–29 °C.