The flow around a square cylinder at Re=22 000 is simulated with large eddy simulation (LES).The effect of boundary condition is studied.A mixed finite-volume finite-element method with unstructured grids is adopted to solve filtered compressible Navier-Stokes equations.Though the numerical accuracy is only second order and the grids is relatively coarse,the results are satisfactory and even better than those with much finer meshes.