Based on a station foundation pit of Shanghai Metro Line 23, this paper studies the application of steel support wireless servo system in deep foundation pit excavation and support, and analyzes its closed-loop control core of "real-time monitoring - data feedback - automatic axial force compensation". The system composition and working mechanism are described, and its application effect is verified by field measured data. The results show that the system has real-time response, precise regulation and high automation. The average lateral deformation of retaining structure in servo control area is 23.26 mm less than that in non-servo area. It can effectively restrain foundation pit deformation, reduce excavation disturbance to surrounding buildings and underground pipelines, and provide reference for similar projects.