AbstractWith the development of hydraulic engineering, more hydropower stations are built in the complex geological condition. This work proposed a case study on stilling basin in complex fractured dam foundation using 3D nonlinear analysis. A detail implementation of the numerical mesh generation from profile to solid geometry using boundary representation (B-Rep) is illustrated. Considering the main factors like self-weight, hydrodynamic pressure, and uplift pressure, the stress and deformation results of stilling basin in complex fractured foundation are obtained. According to the calculation and analysis, the design stilling basin can meet the engineering requirements of hydraulic structure. However, it is suggested to carry out the necessary foundation treatment for the sericitized slate as well as fracture plane. The study will provide valuable reference in the analysis of related engineering.