According to the reaction shaft operation characteristics during the flash smelting process, 15 groups of slag samples containing high Fe3O4were prepared by some chemical reagents, and then the slag surface tensions were measured using a RTW-10 type synthetic test instrument for melt physical property by means of suspension link. The effects of temperature ( T ), basicity ( B ), the Fe/SiO2ratio (mFe/mSiO2), Fe3O4content (ωFe3O4), Cu2O content (ωCu2O), MgO content (ωMgO) and CaO content (ωCaO) on the slag surface tension (δ) were also studied. Results show that δ fluctuate between 0.3N/m to 0.8 N/m, and is increased with the increase of T, B, mFe/mSiO2, ωCu2O, ωMgOand ωCaO, and with the decrease of ωFe3O4, under the range of slag contents: mFe/mSiO21.36~1.78, ωFe3O417.83%~21.18%,ωCu2O3.51%~8.34%,ωMgO2.21%~6.57%,ωCaO6.22%~9.87% and the temperature range of 1380°C to 1500°C. To make the freeze slag adhere to the reaction shaft inner wall easily, the Fe3O4content in freeze slag should be increased and the inner chamber temperature of reaction shaft should be controlled appropriately.