In order to assess the performance of the two-dimensional (2D) large eddy simulation (LES) as a computational tool for analyzing separated flows. LES in various models has been developed to simulate turbulent flows, especially to separated flows. In this investigation, 2D LES is used to simulate flow past a wind turbine airfoil in deep stall which is a classical separated flow proved by experiments. The results of 2D LES are compared with that of a 3D model using RNS/LES hybrid methods and with experimental data. This shows that the 2D LES method can not only be used to simulate separated flows, but also the calculation time of 2D LES is significantly decreased to compare with the 3D model using RNS/LES hybrid methods.