Abstract: A computational fluid dynamics model for the smoke flow in a grooved filter was developed in order to study the flow field distribution in the grooved filter and the outflowing smoke ratio (the proportion of cigarette smoke leaving the grooves accounting for the total smoke entering into the grooved filter). By means of the developed model, the smoke flow in grooved filter at an average velocity of ISO smoking regime was simulated, the distribution of velocity and pressure of cigarette smoke in grooved filter was obtained, and the ratio of smoke leaving the grooves was calculated. The effects of factors such as the shape, number and depth of grooves on the ratio were investigated as well. The results showed that:1) The ratio of smoke leaving the grooves slowly increased first and then gradually decreased with the increase of groove length. 2) The said ratio linearly increased with the increase of groove number. 3) The groove shapes affected the ratio in the order of rectangular > triangle > trapezoid. The simulation results well agreed with study results by other researches.