The aerodynamic performance of blunt trailing edge airfoils has been investigated. The flow fields around 2D modified NACA64-418 which consists of the tip blade of wind turbine after repair have been analyzed. To mimic the repair airfoil, the original NACA64-418 airfoil is modified by adding thickness method which is made by symmetrically adding thickness to either side of the camber line. The polynomial equations of modified airfoil surface is obtained by the curve fitting of the least square method. The numerical results show that the drag is increased but the lift doesn"t change a lot when the thickness of trailing edge increases. Also, the pressure distributions around the surface of modified NACA64-418 are similar.