The invention discloses a method for preparing a medical intermediate 5, 10-diarylpyrido[4, 3-b][1, 6]naphthyridine derivative, and belongs to the technical field of biological medicine preparation. The method for preparing the medical intermediate 5, 10-diarylpyrido[4, 3-b][1, 6]naphthyridine derivative by acidic ionic liquid catalysis includes: taking aromatic aldehyde, amine and 2, 4-piperidinedione as the reaction raw materials, adopting an ethanol-dimethylformamide-water mixed solution as a reaction solvent, and performing catalysis by an acidic ionic liquid catalyst to obtain the 5, 10-diarylpyrido[4, 3-b][1, 6]naphthyridine derivative. The preparation process provided by the invention has the advantages of high product yield, recyclable catalytic system, short reaction time, simpleand convenient product purification process and the like.