An acoustic propagation model of jetflow was deduced by geometrical acoustics based on the fanshaped stratified velocity model of shear layer built by CFD. Taken an actual openjet wind tunnel as research objects, the velocity characteristics of jetflow were given by numericalsimulation. A fanshaped stratified velocity model of shear layer whose speed changed uniformly with the angle, was built. The acoustic propagation between different velocity layers was deduced by using the sound refraction theory. The acoustic propagation model of jetflow was verified by aeroacoustic wind tunnel experiment which took sound source drift as the index. The results show that this acoustic propagation model is more accurate to predict sound drift. In conditions that jet flow velocity is high and shear layer thickness is large, the improvment is particularly evident.