The viscous resolution of different CFD schemes for vortical flows over delta wings has been investigated both numerically and theoretically, which include Jameson's center scheme, Roe's FDS scheme, Van Leer's FVS scheme and upwind TVD scheme. It has been concluded that Jameson's center scheme and Roe's FDS scheme have the best viscous resolutions, while Van Leer's FVS scheme and upwind TVD scheme are not suitable for vortical flow simulations.