The invention discloses a method for preparing polysubstituted pyridine. The method comprises the following steps: dissolving a 1,5-dicarbonyl compound into DMSO (dimethyl sulfoxide) in a stirring manner, weighing and adding an ammonium acetate solid into a solution of the DMSO at one time, and heating and stirring a mixed solution; checking whether reaction is completed or not by virtue of a thin layer chromatography plate, cooling the reacted mixed solution to room temperature, diluting the reacted mixed solution with ethyl acetate, and washing an ethyl acetate layer for 3 to 5 times with de-ionized water; evaporating an organic phase of the ethyl acetate layer to dryness under reduced pressure, and recrystallizing a concentrate with dichloromethane to prepare a 1,2,3,5-tetra-substituted pyridine product. According to the method, the DMSO is adopted as a solvent and an oxidant, and the 1,5-dicarbonyl compound is enabled to react with ammonium acetate to generate 1,2,3,5-tetra-substituted pyridine under a heating condition. A reaction system is simple, addition of an additional oxidant and the conditions of high temperature and intense heat are avoided, and the method is particularly suitable to a pyridine structure of which three positions are substituted with ester groups.