Abstract: The contents of formaldehyde,acetaldehyde,acrolein,acetone,propionaldehyde,crotonaldehyde,methyl acrolein,2-butanone,butyraldehyde,benzaldehyde,valeraldehyde,hexanal in mainstream smoke of 32 cigarette samples were determined by way of derivation with 2,4-dinitrophenylhydrazine(2,4-DNPH) and analysis with LC-MS/MS.The recoveries of aldehydes and ketones were in the range of 91.6% to 100.3% with the relative standard deviations of 3.28% to 7.86% and the limits of detection of 0.1 to 0.5 ng/mL.The major volatile aldehydes and ketones in mainstream smoke of samples were acetaldehyde and acetone,while the contents of benzaldehyde and hexanal were lower.The contents of volatile aldehydes and ketones in domestic Virginia cigarette smoke were higher than those in imported cigarettes,while those in blended cigarette smoke were contrary.Higher tar delivery always means higher volatile aldehydes and ketones contents regardless of cigarette type.