Abstract: In the simulation of engineering flow problems, the corner usually causes flow separation, which has a great impact on the development of the downstream flow. Therefore, the accurate simulation of the flow at corner positions is quite important, especially to clarify the influence of the meshing strategy at corners on the accuracy of spatial discretization has great research significance. The paper analyzes the spatial discretization method using unstructured grid, and investigates the commonly used unstructured grid boundary layer meshing strategy and computational accuracy by analyzing the high Reynolds number flow around square cylinder. The results show that the orthogonality, skewness and aspect ratio of the boundary layer mesh at the corner have a great influence on the simulation results of the overall flow field. It also gives the suggestion of the unstructured mesh at the corner position, which can provide reference for the mesh distribution and flow field simulation of similar shape engineering problems.