The traditional slag/metal equilibrium technique cannot be applied to the direct measurement of the distribution of phosphorus between slag and carbon-saturated hot metal for slag with higher iron oxide contents. In this paper, the indirect measurement approach was used, i.e. to measure the distribution ratio of phosphorus between slag and solid iron and then to obtain the ratio between slag and carbon-saturated hot metal through conversion, and the dephosporisation capacity of CaO–FeO*–SiO2–P2O5(15%)–CaF2 systems at 1573⋅15 K (1300°C) was investigated. In the mean time, the techniques of scanning electronic microscope, energy spectrum analysis and X-ray diffraction were applied to study the form of phosphorus presence in the dephosphorisation slag. The results demonstrated that (i) the phosphorus distribution ratio decreases with an increase in (FeO*) at higher basicity of about 7⋅0, (ii) when the CaO/SiO2 ratio is bigger than 3⋅76, the phosphorus distribution ratio decreases with an increase in the CaO/SiO2 ratio, (iii) higher phosphorus absorption capacities can be ensured by reasonably decreasing CaO/SiO2 at higher (FeO*), (iv) the phosphorus-containing phases are liquid slag and Ca5(PO4)3F and the range of phosphorus content in these two phases are 2⋅45–4⋅25% and 22⋅99–27⋅16%, respectively.