Abstract: A method to analyze behaviors of beam-slab braced foundation pits was proposed considering the effect of construction process.A 3D FEM program based on the model was developed.The method was used to analyze the deformation and internal forces in the retaining structure and the beam-slab bracing system of a deep foundation at different excavation stages.The analytical results were compared with the measured data.It was indicated that the suggested method could be used to simulate the excavation process of complex foundation pits.It was also shown that the beam-slab bracing system was an effective way to control the displacement of large and deep foundation pit.