Abstract: The nitrogen oxides(NO_x) in mainstream smoke of 192 domestic and imported cigarette samples were determined with chemiluminescence method,and the statistical difference of NO_x deliveries of cigarettes was analyzed.The results showed that:1) The average NO_x delivery of domestic cigarettes was significantly less than that of imported ones.2) The differences of NO_x deliveries among cigarette types were significant,in which the NO_x deliveries of blended cigarettes were the highest,either domestic or imported,imported Virginia type cigarettes the next and higher than those of domestic Virginia type cigarettes.3) The NO_x deliveries of middle and high grades domestic Virginia type cigarettes were lower than that of low grade ones.4) There was no significant difference of NO_x deliveries between cigarettes produced in different years.