Abstract: The delayed detached eddy simulation（DDES） based on shear stress transport（SST） model was performed to simulate the flow filed in a gasoline engine under steady state. The simulation results were first validated against the experimental data measured by 3D-particle image velocimetry（PIV） on an optical engine. Then,the spatial domain and frequency domain of turbulent flow in cylinder were analyzed. The comparisons of simulation results of DDES with experimental data and calculation results of Reynolds-averaged navier-stokes（RANS） indicate that the DDES has great advantages in simulating the complex flow in the cylinder. The results show that the flow symmetry trend in tumble center plane under high valve lift condition is better than that under low valve lift condition,and three-dimensional flow concentrates in the combustion chamber and the region under intake valves.The Reynolds number of mean flow determines the overall characteristics of turbulent energy spectrum in the cylinder. In the region with higher Reynolds number of mean flow,the scale of vortex whose turbulent energy enters inertial transport becomes smaller. Turbulent Reynolds number mainly affects the length of inertial sub-region. The turbulence develops more fully and the inertial sub-region becomes more obvious at higher turbulent Reynolds number. The square of turbulence intensity represents the area surrounded by the turbulence spectrum,and relative turbulence intensity affects the turbulence energy density in low frequency.