Smoking behaviour is a comprehensive action with various smoking characters affected by sociological factors and cigarette itself. To investigate the smoking behaviours of smokers of different tar yield cigarettes, molecular epidemiology, including epidemiological survey and biomarker determination, were adopted to study smoking behaviours and their influencing factors. On the basis of cross-sectional design, 435 adults (aged > 18 years) were categorised into four groups: non-smoker, low-tar, moderate-tar and high-tar groups. The urine samples were collected from each group. The metabolites of eight biomarkers, nicotine, tobacco specific nitrosamines, polycyclic aromatic hydrocarbons, 1,3-butadiene, acrylonitrile, acrolein, crotonaldehyde and benzene, in urine samples were determined by HPLC-MS/MS. The results showed that: 1) The differences of age, gender, education, occupation and income reached statistically significant levels (P<0.05) among different groups, while no significant statistical difference (P>0.05) was observed in the factors of marriage status and body mass index. 2) There were no significant differences in cigarette number (P=0.572, >0.05), puffing interval (P=0.443, >0.05), depth of inhalation (P=0.934, >0.05), butt length (P=0.854, >0.05), nicotine dependence (P=0.149, >0.05) among different groups. The number of cigarettes smoked by a smoker did not change significantly (P>0.05) when the smoker switched to higher or lower tar yield cigarettes. 3) The metabolite levels of nicotine, tobacco specific nitrosamines, crotonaldehyde, acrolein, 1,3-butadiene, acrylonitrile and benzene in the urine of smokers in low- and moderate-tar groups were significantly (P<0.05) lower than those in high-tar group; however, the metabolite levels of polycyclic aromatic hydrocarbons did not differ significantly (P>0.05) among different groups. It was indicated that smoking behaviours were affected by age, gender, education, occupation and income; the tar yield of cigarette was not a main influencing factor of smoking behaviours. The exposure level of smokers of low tar yield cigarettes to hazardous compounds is lower than that of moderate or high tar yield cigarettes.