Abstract: A two-dimensional incompressible diffuser flow was numerically simulated employing no staggered grid arrangement and incompressible SIMPLE method to solve GAO-YONG turbulence equations. The problem of checkerboard prediction of pressure was cured by evaluating the cell face velocities by the momentum interpolated principle. In order to improve the calculation precision, an orthogonal body fitted coordinate system was selected and a second-order QUICK discretizationfor the convective part was used. The calculation results such as velocity profiles and friction coefficients are finely close to the experimental data and better than the results of BL(Baldw-Lomax) model. It shows the GAO-YONG turbulence equations can predict the real turbulent flow with pressure gradient well without using empirical coefficients and wall functions. The calculation proves that it is important to the GAO-YONG turbulence equations for simulating adverse pressure gradient flow to introduce the effect of mean pressure gradient into energy equation which describes the characteristic length scale of the turbulent flow.