Abstract: The flatbact (blunt trailing edge) airfoils are adopted for the inboard region of large wind turbine blades due to their structural and aerodynamic performance advantages. Very limited experimental data at high Reynolds numbers makes it difficult for wind turbine designers to design and use these section shapes because the wind tunnel experiments are limited by the Reynolds number and solid blockage. In this study, a 2D Reynoldsaveraged NavierStokes solver coupled with a transition prediction code based on en method is used to CFD calculation of blunt trailing edge airfoils. A new coupling structure with a timeaccurate transition prediction model taking into accounting the unsteady flow as a result of the bluffbody vortex shedding is developed. An airfoil of DU97Flat modified by DU97-W-300 airfoil for wind turbine application is calculated and effects of grid points are investigated. The aerodynamic performance indicators of DU97-W-300 are calculated and compared with Timmer′s wind tunnel experiment results.It shows that the indicators calculated from the method illustrated in this study agree much better to Timmer′s wind tunnel experiment results compared to other results from literature while with much less gird numbers.