Research conclusions: When open excavation construction is carried out in deep excavation of city subway transfer station under complex environment, in-situ monitoring is a useful measure for safety guarantee to information construction. For subway station with complicated shape, compound maintenance forms that it includes retaining pile, steel support and anchor cable should be adopted to be as supporting structure of deep excavation. Stratified excavation method of earthwork and applying prestress to steel support are the important measure of reducing spatial effect and guarantee safe construction. FLAC numerical simulation is important means for the study of deep excavation deformation law.