Abstract: In order to study the characteristics of linear and rotary smoking machines in the determining of total particulate matter(TPM),moisture content,nicotine,tar and CO yields of cigarettes under health Canada intense smoking regime(HCI),a comparative study involving 9 linear smoking machines and 8 rotary smoking machines smoking 10 cigarette samples were carried out.The results demonstrated that:1) For TPM,moisture content and tar,the deliveries determined by linear smoking machines were higher by 2.4-7.6,2.0-5.0 and 1.4-3.1 mg/cig.than did by rotary smoking machines,respectively.While for CO,the delivery determined by linear smoking machines was lower by 0.9-2.4 mg/cig.Paired t-test results indicated that there existed statistical significant differences between the deliveries of TPM,moisture content,tar and CO determined by linear and rotary smoking machines at the confidence level of 99%.2) Nicotine deliveries determined by linear and rotary smoking machines were similar and there was no significant difference at the confidence level of 0.01.3) Comparing with rotary smoking machines,linear smoking machines showed higher repeatability and reproducibility for TPM,water and tar,and higher reproducibility for nicotine determination;while showed lower reproducibility for CO determination.Paired t-test results indicated there existed statistical significant differences between the deliveries of TPM,water,tar and CO determined by linear and rotary smoking machines at the confidence level of 99%.4) The repeatability for nicotine and CO determination by linear and rotary smoking machines had no significant differences at the confidence level of 0.01.