Abstract: Based on field experiments,the amount of rephosphorization quantity,the P content of alloy and auxiliary materials and the quantity of tapping slag were calculated in order to effectively control liquid steel rephosphorization.The effects of slag composition and temperature on the rephosphorization were also analyzed in the paper.The results show that the rephosphorization caused by alloy addition and tap-ping slag were the dominant roles contributing to the total rephosphorization quantity.Adding alloy with low P content and decreasing the tapping slag amount could effectively reduce the rephosophorization quantity.Controlling tapping temperature at~1620℃ and the content of FeO greater than 15% were necessary measurement in order to reduce rephosphorization.During secondary refining,controlling the slag basicity and the content FeO of refining slag ranging from 0.25% to 0.45%,liquid steel rephosphorization can be effectively controlled.