In an excavation projects with high groundwater level, the geometric dimensions (length, width and depth) of pit, the groundwater level, the permeability of soil layers, economic considerations and pit implementation scheduling are the most important factors which influence the design of dewatering system. In this paper, with assuming of WellPoint system used as a case study at Boushehr port, in order to determination of water flow which discharge from well points and cause reduction of water table level in to the final excavation level and with assumption of constant parameters like distance between WellPoint, spacing between wellpoints and excavation facing and wellpoints radius, Both numerical and theoretical analyzes have been done. Comparison of results for this case study show that design of WellPoint system based on theoretical analysis leads to higher flow estimation than amount which calculated by numerical analysis.