The powder metallurgy method of raw material powder mixing, billet pressing and sintering molding is widely used in the preparation process of molybdenum alloys. Therefore, the uniformity, purity, powder size and morphology of the raw material powder have an important influence on the properties of the molybdenum alloy product. In this paper, the precursor powder was prepared by solution spray drying, and the precursor powder was reduced to molybdenum-tungsten alloy powder or molybdenum-niobium-nickel composite powder by high temperature reduction under hydrogen atmosphere. They were studied that the effects of the spray drying process parameters (solution concentration, feed rate, drying temperature, etc) and reduction heat treatment process parameters (reduction atmosphere, temperature, time, etc.) on the particle size, composition and morphology of molybdenum alloy micropowder. Furthermore, the brazing property of molybdenum-niobium-nickel composite powder was analyzed. The result show that spherical molybdenum-tungsten solid solution alloy powder with the particle size of 0.5~3μm and spherical molybdenum-niobium-nickel composite powder with the particle size of 0.5~2μm can be obtained by solution spray drying combined with reduction heat treatment. Molybdenum-niobium-nickel composite powder has excellent wettability when it was brazed on molybdenum plate.