The invention discloses a copper and molybdenum alloy for electric vacuum and a preparation method of the copper and molybdenum alloy for electric vacuum and belongs to the technical field of refractory metal powder metallurgy powder manufacturing. The copper and molybdenum alloy comprises 3-10wt% of molybdenum and the balance copper. Molybdenum powder or molybdenum powder with the surface coated with the copper and copper powder serve as raw materials, and the copper and molybdenum alloy is acquired through material mixing, compression molding, hydrogen reducing activation and densification treatment. Molybdenum powder particles in the alloy are distributed uniformly, the density is not lower than 99%, and a material guarantee is provided for a low gas emitting amount, high gas tightness, high heat conductivity and medium strength copper alloy. The preparation method can be achieved on an existing powder metallurgy production line, scale production is easy, and the production efficiency is high.