The invention discloses a method for catalyzing one-step synthesis of flavonoids by using 1,3-dialkylimidazole oxometalate. ‑Hydroxyacetophenone or 2‑hydroxyacetophenone derivatives, ionic liquid catalyst, and organic solvent, stirred and heated to 50-90°C, then using oxygen or air as oxidant, reacting at constant temperature for 2-7 hours, cooling, and depressurizing After separation by distillation, column chromatography and recrystallization, the target flavonoids are obtained. The biggest feature of the present invention is that ionic liquid is used as a catalyst, and the yield of one-step synthesis of flavonoids is as high as 85%. Therefore, compared with the existing synthesis method, the present invention shortens the reaction steps and significantly improves the synthesis of flavonoids Efficiency, with the advantages of high product yield, low production cost, simple operation steps, mild reaction conditions, etc., so it is considered to be a new method for efficiently synthesizing flavonoids.