Abstract: The particulate matter in the mainstream smoke of cigarettes was trapped by the cambridge filter and the matters in gaseous phase of the smoke were absorbed in isopropyl alcohol and ethanol by 2 collision traps in series.Moisture contents in the 2 analytes were determined by gas chromatography.Linearity range was obtained between 0.8-6.0 g·L-1 with recovery in the range of 93.46%-106.15% and RSD less than 2.5%.The proposed method was applied to the determination of moisture in mainstream cigarette smoke of seven kinds of cigarettes.The contents of total moisture content found were 6.77-9.43 mg·cig-1,and the moisture content in gaseous phase matters attained to 65%-75% of the total content.As shown by these results,moisture content in the gaseous phase matter was an important parameter in studying the quality of cigarettes.