This paper mainly researches the volatile phenomenon of V2O5 at high-temperature and the appropriate additions to depress volatilization of V2O5 effectively during direct alloying with V2O5 to smelting vanadium steel. It shows that the volatilization loss of V2O5 is 4.34% when V2O5 is heated to 1600°C for 10 minutes. The reductant ferrosilicon and additives CaO can depress the volatilization of V2O5 effectively. The volatilization loss of V2O5 decreases to 1.55% at 1600°C when the mass ratio of ferrosilicon to V2O5 is 1:1. CaO can react with V2O5 to form calcium vanadate to decrease the activity of V2O5. The volatilization loss of V2O5 decreases to 1.82% with adding 48.0% CaO in the V2O5–CaO system at 1600°C. The volatilization loss of V2O5 with adding more than 30% CaO can decrease to 0.48% when keeping the mass ratio of ferrosilicon to V2O5 is 1:1.