The flow inside a high-pressure turbine is a fully 3-D, unsteady flow, which has a great influence on the aero-thermal performance and structural strength of high-pressure turbines. In order to better understand the flow mechanism and guide the design of modern aero engines, the basic flow characteristics of transonic turbine are investigated in the present study. A modified scale-adaptive simulation (SAS) technique based on the shear stress transport (SST) turbulence model is applied here. Two test cases are carried out to assess the capability of the current model in predicting complex turbulent flows. The results show that the statistical parameters and flow structures of the modified SAS model are in good agreement with the large eddy simulation (LES) result and the experimental data, where the calculation time is significantly reduced compared to LES. In summary, the modified SAS method has demonstrated an excellent spatial resolution in unsteady simulations of turbomachinery, which shows the potential to be applied to realistic engineering applications.