The invention relates to a low-cost preparation method of a composite material with a uniform core-shell structure. The method comprises the following steps: (1) placing a substrate material into a reaction cavity, and vacuumizing the reaction cavity; (2) injecting a catalyst into the reaction cavity, adjusting and controlling the temperature to gasify the catalyst, and depositing the catalyst on the surface of the substrate material; (3) removing the excessive catalyst from the reaction cavity, and vacuumizing the reaction cavity again; (4) injecting a covering material into the reaction cavity, and adjusting and controlling the temperature to gasify the covering material to make the covering material be reacted with the substrate material under the action of the catalyst and cover the surface of the substrate material with a chemical reaction product, thereby forming a core-shell structure blank; (5) taking out the blank, and performing vacuum drying under the temperature of 20 to 160 DEG C for 0.5 to 24 hours to remove the catalyst and the covering material which are left on the blank, thereby obtaining the composite material with the uniform core-shell structure. Compared with the prior art, the low-cost preparation method disclosed by the invention has the advantages of simple steps, easiness in implementation and the like.