Abstract: Deformation monitoring of deep foundation pit is an important content of information construction. In the excavating process of the deep foundation pit project of Gangwan Plaza (Phase 1), according to the horizontal and lateral displacement, internal stress of support structure, subsidence monitoring and so on, combined with intensity detection of perimeter structure, use inverse analysis method to simulate foundation numerical deformation, and forecast foundation pit deformation at different depth. The actual monitoring result is consistent with the forecast value basically, and the reliable basis is provided for foundation pit design and construction.