The design and optimization of advanced aero-engines must be based on a comprehensive understanding of their internal flow mechanisms. As one of the core components of an aero-engine, various forms of secondary flows are formed in the high-pressure turbine (HPT), represented by vortices and waves which cover a range of length scales and time scales. To enhance the understanding of unsteady flow characteristics, a modified detached eddy simulation (DES) technique incorporating the modeling thought of scale-adaptive simulation (SAS) is proposed in the present study. Two test cases are carried out to assess the capability of the current model in predicting complex turbulent flows. The results show that the accuracy of the original DES method based on the shear stress transport turbulence model (Menter SST-DES) is further improved, while the computational cost remains almost unchanged. The statistical parameters and flow structures of the current DES are in good agreement with the large eddy simulation (LES) and the experimental data.