Explore the influence of gas flow conditions geometry of the diesel spiral airway, which predict the performance of the design of the airway. And the direction of improvement and optimization theory, using CFD technology to explore such away preliminary attempt, based on Pro/E to build the model of airway fluid entity, and use a common geometric standard model into the finite element analysis software ANSYS to analyze to get the airway export velocity distribution, turbulent kinetic energy distribution and other results. It is assessed on eddy current level of Angular momentum flux, and airway improved.