The three-dimension substantiality of the TBD620 diesel engine's intake port and combustion chamber was constructed on the Pro/E software platform, and an simulation of the intake process was done with the fluid analysis software FIRE,the effect of the double controllable intake swirl system on the eddy development during the dynamic intake process of the TBD620 diesel engine was analyzed. The results have showed that the intake swirl of the double controllable intake swirl system can ameliorate the diesel engine's mixed gas significantly, the low load combustion performance of the diesel engine is also substantially increased.