The theoretic calculations were performed on reduction thermodynamic of molybdenum oxide powder based on different chemical composition and temperature of hot metal. The scale-up experiments were carried out at 80 t hot metal ladle and results indicate that yield of molybdenum will reaches over 98% by adopting such technical parameters as the size distribution of molybdenum oxide powder being 0. 10 ～0. 15 mm, injection time being 30 ～35 min, injection rate being3. 0 ～3. 5 kg/min.