The composition of copper slag is closely related to the physical properties of slag and the recovery rate of matte during the copper slag cleaning stage. In this work, copper smelting slag is used as raw material, and analytical methods such as mass action concentration model, X-ray diffraction, scanning electron microscopy, and infrared spectroscopy are employed to investigate the influence of FeO and SiO2 on the physical properties and copper loss of copper smelting slag. The results show that as the FeO content in the mass-action concentration system of copper smelting slag increases, the mass action concentration of Fe2SiO4 increases, Fe3O4 show a trend of first increases and then decreases, and as the SiO2 content increases, the mass action concentration of FeO and Fe3O4 decreases, the reducing ability of slag increases and the oxidizing ability decreases. As the addition of FeO increases from 0wt% to 12wt%, the proportion of liquid slag phase in copper slag system increases, the foaming slag gradually disappears, the complex silicate network structure of slag tends to simplify, and the viscosity and melting point of slag decrease, which is conducive to the polymerization and sedimentation of matte. The proportion of matte layer increases from 21.9% to 28.7%, and the loss of copper due to mechanical entrainment decreases from 5.64wt% to 0.71wt%. With the addition of SiO2 increasing from 0wt% to 12wt%, the high-melting-point spinel phase in the copper slag decreases, while the low-melting-point fayalite phase increases, the mass fraction of chemically dissolved copper in the copper slag gradually decreases, and the loss of copper due to mechanical entrainment decreases from 5.64wt% to 1.02wt%. The increase in SiO2 and FeO content in copper smelting slag can improve the fluidity of slag and enhance the recoverability of matte in the electric furnace cleaning stage.