In this paper, taking an ultra-deep foundation pit of a commercial complex in Jinan as the research object, aiming at the difficulties of deep excavation, complex surrounding environment and abundant groundwater, the whole process control research of supporting dewatering design and construction is carried out. According to the control characteristics of the surrounding environment, ten supporting units were designed, instead of the conventional water-stop curtain, the process of dewatering in the pit and recharging outside the pit was adopted, meanwhile, the construction detection standard was established, the multi-dimensional foundation pit monitoring system was established, and the key points of supervision and control at all stages were clarified. The practice shows that the site leveling and unloading greatly reduces the project cost, the innovative dewatering scheme effectively controls the impact on the surrounding environment, and all monitoring indexes of the foundation pit meet the requirements of the specification. The research results provide important engineering reference for similar complex ultra-deep foundation pit projects.