The invention discloses a preparation method of an intercalated composite oil drag reducer used in pipeline drag-reduced conveying of oil, relating to the technical fields of an organic macromolecular compound and a pipeline system. According to the preparation method of the intercalated composite oil drag reducer, the intercalated composite oil drag reducer is a polymerisate which is prepared by performing in-situ polymerization to alpha-olefin monomers in a lamellar structure of silicate through taking phyllosilicate as a main body and Ziegler-Natta catalyst as an initiating system in the presence of an interfacial compatibilizer, wherein the mass ratio of the alpha-olefin monomers to phyllosilicate is (20-25) to 1; the mass ratio of alpha-olefin monomers to interfacial compatibilizer is 100 to 1; and the mass ratio of the alpha-olefin monomers to the Ziegler-Natta catalyst is 1000 to (1-8). The intercalated composite oil drag reducer is prepared by performing in-situ polymerization to polymer monomers among layers of a nanometer intercalated inorganic material, and the product has excellent anti-shear capability and good drag reduction performance.