The invention relates to a method for separating alkaline scent ingredients from the main stream smoke of cigarettes, in particular to a method for separating trace alkaline scent ingredients from alkaline ingredients containing a large amount of alkaloids such as nicotine and the like. The method comprises the following steps of: extracting collected smoke particulate matters, namely unblended cigarettes with high-quality tobacco leaves serving as raw materials, performing acid washing, concentrating, distilling under vacuum and the like to obtain a cut fraction F2 with low alkaloid content;separating the cut fraction by a gas chromatography separation method to obtain 5 cut fractions SF1 to SF5; and performing the combination of gas chromatography-mass spectrometry and sensory evaluation on SF1 to SF5, and selecting a cut fraction SF4 with an obvious sensory effect. By the method, a large number of alkaloid ingredients which do not contribute to the scent ingredients of the cigarettes are removed, and low-content active alkaline scent ingredients are enriched; and the method is applied to the field of the perfuming of cut tobaccos of the cigarettes, and has an important significance for improving the smoking quality of the cigarettes in China.