In order to explore the transformation mechanism of phosphorus during sintering process,minisintering experiment was carried out based on the thermodynamic calculation,and the component and phase of calcined product were analyzed. The results show that the dephosphorization ratio reached up to 20% in the conditions of 4% carbon,1.41% SiO₂ and 1.36% CaCl₂; When adding SiO₂,Ca₅(PO₄)₃F is transformed into Ca₃(PO₄)₂ through defluorination reaction,and then dephosphorization reaction takes place. After adding CaCl₂,the diffraction peak of Ca₅(PO₄)₃F decreases,while diffraction peak of CaSO₄ enhance obviously,at the same time both CaF₂ phase and CaSiO₄ phase appeare,which indicating the occurrence of gasification dephosphorization reaction with PCl₃ as dephosphorization product.