In this study a CFD model of a spark ignition (SI) engine was prepared using KIVA-3V code and experimental data to investigate the in-cylinder flow field. The whole engine cycle was simulated and the validity of the model was ascertained by experimental result of in-cylinder bulk pressure and flow field visualization. The flow pattern inside the cylinder was investigated qualitatively to deepen our understanding of the formation and development of rotational flow prior to the ignition. Both tumble and swirl were observed in the flow field. The numerical results showed that turbulence intensity in the section with stronger vortex is higher.