Abstract: This paper describes systematically our recent researches and advances in rare earth-doped molybdenum. It is shown that no matter under the condition of room temperature, high temperatur or low-temperature, the strength, the embrittlement properties of the molybdenum and its thermionic emission, are greatly improved by the addition of La₂O₃. The rare earth oxides(La₂O₃, Y₂O₃) exhibit an comprenhensive strengthening and toughening effect on molybdenum, which gets the molybdenum toughened with more ductility and lower DBTT while the strength of molybdenum increases. Besides it is proved that rare each-doped molybdenum has better emission properties and lower operating temperature than W-ThO₂. The mechanisms concerned are also discussed.