Abstract: The effects of five primary processing parameters (A: hot air temperature in ordering cylinder, B: cut width of tobacco, C: steam flow rate in HT, D: hot air temperature in dryer, and E: exhaust vane opening in dryer) on the deliveries of tar, nicotine, CO, NH₃, HCN, phenol, crotonaldehyde, B［a］P and NNK in mainstream cigarette smoke were investigated. An experiment of five-factor and three-level was designed by combining D-optimum design, A-optimum design and Ⅳ-optimum design with balance design principle, and the results of the experiment were analyzed by visual analysis, ANOVA and multiple comparison. The results showed that: 1) All of the five parameters affected the deliveries of NH₃ and HCN in the order of B> D> C> E> A; 2) Parameters A, B, D and E affected B［a］P delivery in the order of A> D> B> E; 3) Parameters A, B, C and E affected NNK delivery in the order of E> A> B> C; 4) Parameters A, B, D and E affected nicotine delivery in the order of B> A> E> D; 5) Parameters A and B affected the deliveries of phenol, tar and CO in the order of B>A; 6) Parameters D and E affected crotonaldehyde delivery in the order of E>D.