Abstract: In order to determinate the alkaloids (nicotine,nornicotine,myosmine,anabasine and anatabine) in total particulate matter (TPM) of mainstream cigarette smoke puff by puff,cigarettes were smoked by a modified Borgwaldt RM20/CS smoking machine.TPM per puff of 20 cigarettes was trapped on individual Cambridge filter pad,the filter pad was extracted under ultrasonic,then centrifugalized,the supernatant liquid of the extract was analyzed by GC/MS.The results showed that:1) the relative standard deviations (RSDs) of the 5 alkaloids ranged from 1.33% to 7.58% with the recoveries from 94% to 106%; 2) the per puff deliveries of TPM,nicotine and myosmine in mainstream cigarette smoke showed an ascending trend, especially for TPM and nicotine; 3) the delivery of nornicotine in mainstream smoke of all samples was lower, there was no obvious change between puffs,and the total content of nornicotine in mainstream smoke of blended type cigarette sample F was the highest.4) the per puff deliveries of the 5 alkaloids in mainstream smoke of low tar cigarettes and blended cigarettes,samples D,F and G,were lower than those of other cigarettes.This method is suitable for determining alkaloids in TPM of mainstream cigarette smoke.