In order to study the effects of multifactor variations on cigarette burning behaviour and the release of tar and CO, a mathematical model of the physical and chemical mechanisms of cigarette smoking was used to simulate the influence of cigarette paper permeability, filter ventilation and cigarette filling density on the airflow velocity field, temperature field, char density field and the concentration fields of O₂, tar and CO. The results are presented as images, which intuitively reveal the working mechanism of each factor. With the increase of cigarette paper permeability, more air entered through cigarette paper instead of the combustion cone center, resulting in the slowdown of both tobacco pyrolysis and char combustion reactions and the decrease of tar and CO release. When filter ventilation is increased, the amount of air flowing into the combustion cone decreases and oxygen supply becomes insufficient, which lowers the solid phase temperature, decelerates pyrolysis and combustion reactions simultaneously, and decreases tar and CO release. If the cigarette filling density is increased, the resistance of airflow into the combustion cone increases, causing the slowdown of the combustion reaction and a decrease of solid phase temperature; however the pyrolysis reaction is accelerated due to the increasing amount of cut tobacco, which significantly increases the release of tar and CO. On the basis of theoretical research, a simplified model for predicting tar and CO yields was set up. By comparing our own and others’ experimental data with the predicted values, the average relative deviations were below 7 %, which verified the accuracy of the model.