Abstract: In order to realize the effective enrichment of phosphorus in high phosphorus converter slag, using the Ca O-Si O₂-Fe₂O₃-P₂O₅-MgO-MnO slag with a P₂O₅content of 10% (mass fraction) as the research object, the form of phosphorus in the high phosphorous slag was studied by the laboratory hot state experiment.The effects of basicity and Fe₂O₃content on the enrichment of phosphorus in high phosphorus converter slag were investigated.The results show that the phosphorus element in the high phosphorus converter slag mainly exists in the form of n2CaO·Si O₂-3CaO·P₂O₅ (n C₂S-C₃P) solid solution and the changes of slag basicity and Fe₂O₃content have no effect on the phosphorus occurrence form.The change of basicity has an effect on the production of 2CaO·Si O₂.Too high or too low basicity is not conducive to the enrichment of phosphorus from slag to phosphorus-rich phase.Controlling the slag basicity in the range of 1.5-1.8 is conducive to the full enrichment of phosphorus in slag.Increasing the Fe₂O₃content in the slag can reduce the precipitation of 2CaO·Si O₂and increase the content of P₂O₅in the phosphorus-rich phase, which is favorable for the enrichment of phosphorus in the slag.