The structure angles should be calculated in the process of turbodrill’s cascade blade profile design. The angles are calculated according to the design parameters, which is the inlet and outlet flow angles of the cascade, but while fluid is flowing in the cascade, there are difference betweens the inlet flow angle and inlet structure angle as well as outlet flow angle and outlet structure angle in the cascade. The flow angles can’t be directly considered as the blade profile’s structure angles, so it is necessary to modify the calculated flow angles to obtain structure angles. Through the analysis, in order to improve the performance of the turbodrill, the flow angles should be modified to get the structure angles toward reducing direction. In this paper, the hydraulic efficiency and circumferential force fx are selected as evaluation parameters , cascade CFD models are built and calculated with the different modified angles. What’s more, the modified inlet and outlet flow angle impact on the turbine performance has been analysed , the given angle modification range is greatly narrowed in existing literature, which allow the designers determine modified value easily in the angle modification process.