The invention relates to a preparation method of a molybdenum trioxide/polyaniline layer-shaped composite material and the method is that: an aniline monomer intercalation molybdenum trioxide composition is synthesized in a waterless acetic acid firstly, and then the molybdenum trioxide/polyaniline layer-shaped composite material can be obtained by triggering the aniline monomer polymerization at150DEG C. The prepared molybdenum trioxide/polyaniline layer-shaped composite material has regular ordered layered structure, the even layer interval is 1.127nm, and the heat stability is high. The prepared molybdenum trioxide/polyaniline layer-shaped composite material is characterized in that the modified MoO3 of lauryl amine is used as an intermediate, and molybdenum need not to be reduced during the intercalation process; the waterless acetic acid is used as a solvent when the monomer is intercalated, and the whole reaction is carried out in a non-water system; air is used as an initiatorduring the polymerization stage, and no other impurity ions are introduced, therefore, the products prepared by the preparation method are high in purity, thus improving the product quality.