Abstract: A method for determining the furan in mainstream cigarette smoke by cold trap and gas chromatography-mass spectrometry (GC/MS) was developed, wherein the furan in mainstream cigarette smoke was trapped with cold methanol containing deuterium-labeled internal standard (furan-d₄) and then analyzed by GC/MS under selected ion monitoring mode. The samples of 11 cigarette brands were smoked under ISO and Health Canada Intense (HCI) smoking regimes, then the furan in mainstream cigarette smoke was determined with the developed method. The results showed that the linear correlation coefficient of calibration curve was 0.999 7, the detection limit of furan was 0.028 μg/mL, and recoveries of the spiked standard ranged from 94.2% to 98.5% with the relative standard deviation (RSD) from 3.3% to 4.6% . The furan release in mainstream cigarette smoke under HCI smoking regime was more than two-fold over that under ISO smoking regime. There was a significantly linear correlation between furan release and measured tar levels under ISO smoking regime. This method is suitable for the determination of furan release in mainstream cigarette smoke.