Abstract: Speziale's nonlinear k-ε model is used to calculate the turbulent flow in nonsymmetry diffuser.Attention is focused on effect of the two typical convective difference schemes,“Power-Law” and “QUICK” schemes,on the performance of the models (the standard and nonlinear k-ε models).The results show that both convective difference schemes have little effect on the prediction of the models.So it is no longer to puzzle brain about choice of convective difference schemes,when applying to nonlinear k-ε models.