The invention discloses a preparation method of composite molybdate hollow microspheres, which comprises the following steps of: (1) taking 1 to 4mmol of MCl2 to dissolve into 20mL of water to obtainsolution A, then taking 1 to 4mmol of molybdic acid to dissolve into 20mL of water to obtain solution B, and mixing the solution A and the solution B, wherein M represents Co, Ni, and Cu; (2) taking 10 to 40mmol of urea to dissolve into 40mL of water, adding the solution and uniformly stirring; (3) transferring the mixed solution to a reaction kettle, and performing a reaction for 6 to 12h at a temperature of 120 to 160 DEG C; (4) carrying out extraction filtration and washing, and drying by a vacuum drying oven at a temperature of 40 to 60 DEG C; (5) calcining for 2 to 4h by a muffle furnaceat a temperature of 350 to 500 DEG C. The composite molybdate hollow microspheres prepared by the invention have a large effective contact area and high porosity; a process is simple, and raw materials are cheap and easy to obtain; in the preparing process, a surfactant and the like are not used as structure-directing agents for controlling the morphology; the synthetic polybasic molybdate hollowmicrospheres, due to microstructure characteristics, are expected to show the excellent catalytic activity as a high-activity catalyst in the aspect of producing hydrogen by catalyzing ammonia boraneto hydrolyze for example.