In order to determine the harmful aldehyde and ketone compounds in sidestream cigarette smoke, the influences of each part of trapping device and sample preparation on the determined values of eight aldehyde and ketone compounds were investigated. A method involving trapping, preparing, and determining with high performance liquid chromatography was developed, and the deliveries of eight aldehyde and ketone compounds in sidestream cigarette smoke of 21 samples of domestic and imported commercial available cigarettes were detected. The results showed that the total content of the eight compounds was in the range of 3300 to 4600 μg per cigarette (μg/cig.), in which the content of acetaldehyde was the highest (1600 to 2300 μg/cig.), followed by formaldehyde and acetone (400 to 800 μg/cig.), and the others were within 70 to 250 μg/cig.