Abstract: D large eddy simulation (LES) of the pulsating field for flow around a square cylinder with a Reynolds' number of 22 000 is carried out by use of finite difference method. By using the split operator method, the N S equation is divided into three steps, namely convection, diffusion and propagation steps, to be calculated separately. A two layer model is employed to deal with divergence near the wall of Smagorinsky model. The calculated pressure field, lifting coefficient and Strouhal number accord with the experimental results.