Abstract: This paper takes the construction of diaphragm wall in a five-storey ultra-deep underground metro interchange station in Tianjin as the research object, and analyses the impact of 69.5 m ultra-deep and ultra-thick diaphragm wall trenching construction in soft soil area on the surrounding environment through the measured data and numerical simulation of finite element.The results show that the trenching depth and wall thickness have a significant effect on the surface settlement: the larger the trenching depth is, the overall trend of surface settlement increases, but the growth rate slows down after the depth exceeds 27 m; the increase of wall thickness leads to a steeper settlement curve, and the amount of settlement and the scope of influence expand. Trough wall reinforcement effectively reduces surface settlement, resulting in a smoother settlement curve and a reduction in the width and depth of the trough. The research results provide a theoretical basis and reference for the construction of ultra-deep and ultra-thick ground connecting wall in soft soil areas.