Abstract: A modified turbulence model is proposed to predict the mixing process of supersonic flows. It differs from the ordinary K-KL two-parameter model in taking account of the compressibility, which should not be neglected in supersonic flow.By general approach similar to that for incompressible flow, the turbulent kinetic energy equation is derived for compressible flow（Eqs 10 and 11）. .In the way-similar to the semiempirical method for incompressible flow, the K-KL equation is written as Eqs 18 and 19. The constants in Eqs 18 and 19 are determined by fitting the calculation curve to the experimental data. The free-jet, fully-developed duct flow and. duct flow with supersonic mixing are predicted with this method and compared with the relevant experimental data favorably. It is also shown that it is impossible to obtain the satisfactory predictions for supersonic flow if compressibility effect is not considered.