Abstract: A pump station in the second stage of east route of south to north water transfer project was located in the highly permeable cracked soil stratum, and the maximum excavation depth of the foundation pit was 25. 3 m. In order to ensure the safe operation of adjacent structures, a 3 D seepage-stress coupling model was created by employing MIDAS finite element software, and the deformation law of the adjacent pump station and bridge was studied under condition of foundation pit with unclosed curtain sealing or deep well dewatering, and the influence of curtain depth and elastic modulus of soil was analyzed. The results are as follows. The deformation of the adjacent structures was generally induced by the dewatering process. Comparing with deep well dewatering method, the maximum drop of settlement and horizontal deformation of adjacent structures were 85. 3% and 72. 4%, respectively. Considering the control effect of settlement and economic, the reasonable depth of the unclosed curtain was 8. 7 m for this project, the settlements of the adjacent main and auxiliary powerhouse of pump station and bridge were 3 mm ～ 4 mm, 10 mm ～ 12 mm and 26 mm ～ 34 mm, respectively.