The invention discloses a preparation method of graphite phase carbon nitride@MOF nano-crystals and application for detecting chiral drug enantiomers based on a composite material, belonging to the technical fields of nanometer materials, metal organic frameworks, analytical chemistry and chiral sensing detection. The preparation method comprises the following main steps: blending an aqueous solution of g-C3N4@Co(II) and an alkaline aqueous solution of H2BDC at a room temperature, adding a DMA solution of a ligand L so as to prepare gel, aging, separating, washing and drying the gel, thereby obtaining the product. A graphite phase carbon nitride@MOF nano-crystal sensor constructed by adopting a hybrid material is used for sensitive detection of the content of the chiral drug enantiomers.