A 3D numerical model was performed to simulate the different cases of the water flow across different-shaped square cylinders. Figures of streamlines and turbulent kinetic energy contour lines in different cases were obtained. Through the comparison of streamlines, the areas of strong turbulent kinetic energy and the strongest turbulent kinetic energy nucleus, the results indicated that,(i) two symmetrical vortexes were formed behind the regular quadrilateral square cylinder and the “⊥”-shaped square cylinder ,respectively, and the former were bigger than the latter .While the flow crossed the “±”-shaped square cylinder without forming vortex.(ii) When water flowed around different-shaped square cylinders, from the regular quadrilateral one, the “⊥”-shaped one to the “±”-shaped one, successively, the strong turbulent kinetic energy distribution area, in which turbulence kinetic energy value was above 18,gradually increased; while the strongest turbulence kinetic energy nucleus, whose value of turbulence kinetic energy was the largest among turbulence kinetic energy nucleuses in the strong turbulent kinetic energy distribution area, moved forward gradually and its area was smaller and smaller.