Large eddy simulations were used to model the three-dimensional flows around a non-submerged spur dike. Based on the rigid lid assumption, all these vortex flows around the spur dike, which probably affected the whole flow field, were numerically simulated and analyzed. The largest circulating flow region caused by the spur dike behind it was weak, which would naturally lead to sedimentation for silt-laden two-phase flows. Based on the Smagorinsky model, the finite volume method was used to discretize the Navier-Stokes equations, and the SIMPLEC algorithm was used to solve them. Meanwhile, these flows were investigated experimentally in a 0.5-m wide flume with a dike placed as a barrier. The computational results are in a fairly good agreement with the experimental data.