Abstract: A prediction method has been developed for average parameters of 2-D subsonic diffuser with uniform shear velocity profile at inlet. A complete solution of all flow parameters can be obtained by interacting the zonal models and coupling them on common boundaries. The momentum integral and the entrainment equations are used for the boundary layer zone. The equations are closed by use of the improved Cole's wall-wake velocity profile. Due to different development of the boundary layers on the upper and lower walls of diffuser under conditions of the shear velocity profile in core flow, different equations are employed. Three actual diffusers are calculated by this method and experimented by authors. The predictions by this method for the streamwise distribution of pressure coefficient, velocity of core flow and the location of detachment are in good agreement with test data.