Abstract: To investigate the effect of the deoxidation processes on the oxygen mass fraction in the molybdenum and niobium powders, the molybdenum and niobium powders were pressed into the round rod specimens with a diameter of 17 mm after ball-milling for 48, 72, 96, and 12h. The Mo-Nb round rod specimens were treated by the hydrogen deoxidation at low and medium temperatures, the vacuum deoxidation at medium and high temperatures, and the hydrogen deoxidation at high temperatures, respectively, to analyze the oxygen mass fraction, microstructure, and sintered density of Mo-Nb specimens after deoxidation. In the results, the mass fractions of oxygen and hydrogen are not significantly increased by ball milling. After the hydrogen deoxidation at low and medium temperatures, the oxygen content by mass of Mo-Nb round rod specimens shows an increase obviously. After the vacuum deoxidation at medium temperature, the oxygen content by mass of Mo-Nb specimens decreases, the effect of vacuum deoxidization at high temperature is further enhanced, and the sintered density of Mo-Nb specimens increases significantly after the vacuum deoxidization, indicating that the deoxidization can be achieved by high temperature vacuum. The oxygen mass fraction of Mo-Nb specimen is close to 0.11% after the hydrogen deoxidization at high temperature.