A three-dimensional computational fluid dynamics (CFD) model for gas flow through a serrated valve tray was presented. The flow field, as well as the dry-pressure drop of the valve under the full-opening condition was simulated based on the proposed model by using FLUENT 6.0 software. Compared with the values of dry-pressure drop in different turbulent models, the simulated results using RNG k-epsilon model are in reasonable agreement with experimental data, indicating that RNG k-epsilon model is suitable in simulating gas flow through the serrated valve tray. Then the CFD model combining RNG k-epsilon model was used to study the three-dimensional gas flow through the considered serrated valve tray. The simulated results showed that various eddies existed on the serrated valve tray, and both the eddy and the non-eddy areas were nearly equal. The existence of addendum can decrease the eddy area caused by gas passing through the lateral outlet slots. The size of eddies can be reduced by optimizing the distance between valves.