The invention relates to a preparation method of a molybdenum alloy material, particularly a preparation method of a Mo2B-reinforced molybdenum alloy. The method comprises the following steps: inducing high-temperature thermit reaction among raw materials Al, B, MoO3 and SiO2 powder in a hypergravity field (1000-5000g), and carrying out quick separation, densification and cooling on the metal melt-ceramic melt mixed product after thermit reaction to respectively obtain a metal solid and a ceramic solid, wherein the metal solid is the Mo2B-reinforced molybdenum alloy. The Mo2B-reinforced molybdenum alloy prepared by the method has the characteristics of high density, high hardness, simple preparation method, short preparation period, low cost and the like.