Abstract: A predicting method of wing turbulent separation area and the influence of different turbulent models on the results of prediction are introduced. The authors analyze the defects of C-S model used in the calculation of separation flow, put forward some improvement schemes and illustrate their application effect through the calculation of concrete examples. Besides, The, technical details and skills for solving the problems about boundary layer separation flow using k-equation model are also given. The calculation results are compared with the algebra model results and the experiment results. The results show that it is necessary to make some improvements on the C-S turbulent model in the original form, including using direction flow displacement thickness to replace 3D displacement thinckness and considering surface flow angle in definition of outer layer viscous coefficient, and the pressure gradient effects and the transverse/ longitudinal viscosities ratio should be considered in definition of the inner layer viscous coefficient.