A 2，4-dinitrophenylhydrazine colorimetric method was developed for the rapid determination of aldehydes and ketones in cooking fumes．The method was based on the formation of a yellow phenylhydrazone compound from the carbonyl groups of aldehydes and ketones，and 2，4-dinitrophenylhydrazine under heating and acid catalyzed conditions，which further produced a red or burgundy-coloured chromogenic substance under strongly alkaline conditions．Separation of the chromogenic substance from 2，4-dinitrophenylhydrazine at the maximum absorption peak of UV-visible spectrum could be used for the detection of aldehydes and ketones．The optimal conditions for the reaction were as follows：reaction temperature：60 ℃，reaction time：30 min，volume of concentrated hydrochloric acid：45 μL，ratio of aldehyde to hydrazine：1∶50，amount of alkali：2.0 mL 60 g/L KOH solution．Under the optimized conditions，the method could be carried out with simple operation，high sample throughput and wide linear range（2.5－15 μmol/L）．It was applied to the analysis of actual catering oil fume samples，with spiked recoveries of 80.0%～84.0% and relation standard deviations（RSD） less than 5%．This method provides a reference for the rapid and efficient determination of high-concentration aldehydes and ketones in cooking fumes.