Abstract: The flow around a square cylinder is a canonical test-case of bluff body flows which includes a lot of phenomena in fluid mechanics. Nevertheless, it is still a great challenge to predict such kind of flows accurately. In current work an in-house large-eddy simulation (LES) code was employed to simulate flow around an isolated square cylinder, where Mach number was 0.3 and Reynolds number was 22 000 respectively, and the subgrid-scale (SGS) model was dynamic Smagorinsky model. Preliminary analysis of the numerical results suggests that time-averaged flow field and Reynolds stress components are in good agreement with existing experimental and direct numerical simulation (DNS) results, which indicates the reliability of the present work. Moreover, instantaneous flow field was analysed to display separation and transition process of the flow and the whole process of vortex shedding in the wake region. This work laid the foundations for more in-depth analysis of relevant flow physics.