Abstract: The innovation and development of construction techniques for underground retaining structures prompts the construction of ultra-deep and specially-shaped diaphragm walls. Based on years of diaphragm wall construction experience and successful construction cases featuring specially-shaped diaphragm walls with extreme depth in Yujiabao, Tianjin, this paper presents the key points of construction techniques for this type of diaphragm wall, i.e., trench construction technology with the combination of a hydraulic grab and reverse circulation drilling rig, an empirical formula of verticality control for a specially-shaped ultra-deep diaphragm wall and the flexible connection method used for the rigid joint of a diaphragm wall. This study expands the scope of application for specially-shaped ultra-deep diaphragm walls.