Flow plays a very important role in internal combustion engine working process.Well-organized flow can improve combustion,increase thermal efficiency and reduce emission.As a cost effective and time saving method,numerical simulation can provide the detailed effect of geometric parameters and is widely employed in ICE flow study.The current research situation of numerical simulation in ICE flow is summarized.The current numerical simulation techniques have not really used to optimize the structure design is indicated.The future research directions of numerical simulation in ICE flow are presented.