Abstract: To investigate the effects of different sample placing modes during temperature and humidity conditioning on main physical properties of cigarettes, the effects of two common sample placement methods (Method 1, cigarettes packed in a packet without the small bottom connected with the tobacco end of cigarettes; and Method 2, loose cigarettes placed in a basket) on the equilibrium state of cigarette weight and the cigarette physical indexes, such as draw resistance and total ventilation rate were studied. The results showed that: 1) The moisture content and weight equilibrium time of cigarettes differed greatly between the two placement methods. The weight of loose cigarettes reached equilibrium after conditioning for 48 h, while that of packed cigarettes increased continuously with the conditioning duration. 2)The influences of the sample placement methods on the main physical indexes of cigarettes were different, the effects on cigarette hardness were the greatest and could cause the variation of hardness determination result, and the effects were significant on cigarette weight and were slight on the draw resistance, total ventilation rate, circumference and length of cigarettes. Within the same conditioning duration, the weight, draw resistance, total ventilation rate, circumference and length of loose cigarettes were all higher than those of packed cigarettes, however hardness was on the contrary. 3) The standards of atmosphere for conditioning and testing of tobacco and tobacco products should clearly define the sample placement method in order to eliminate its effects on test results due to different methods. Placement Method 2 (loose cigarettes placed in a basket) was more suitable according to the conclusions of this study.