Abstract: In order to determine low aldehydes and ketones in mainstream cigarette smoke rapidly and accurately, a method was developed by trapping cigarette smoke with an acidic solution of 2,4 -Dinitrophenylhydrazine, a deriving agent, using pyridine as a stabilizer, and determining the low molecular weight volatile aldehydes and ketones in samples by high performance liquid chromatography with a diode array detector. The CV of this method was below 5% and the average recovery of volatile aldehydes and ketones was over 95%. The five compounds, formaldehyde, acetaldehyde, acrolein, acetone and propylaldehyde, in the mainstream smoke of seven brands of cigarettes were determined by an external standard method. This method was simpler, faster and suitable for analysis of low aldehydes and ketones in mainstream cigarette smoke.