This work focuses on the study of flow around cylinder with both Particle Image Velocimetry (PIV) experiment and Computational Fluid Dynamics (CFD) simulation. PIV measurements of the flow field at the downstream of the cylinder are first presented. The boundary conditions for CFD simulations are measured in the PIV experiment. Then the PIV flow is compared with both RANS (2D) and LES (3D) simulations performed with ANSYS Fluent. The velocity vector fields and time histories of velocity are analyzed. In addition, the time-averaged velocity profiles and Reynolds stresses are analyzed. It is found that, in general, LES (3D) gives a better prediction of flow characteristics than RANS (2D).