The observating and theoretically analyzing inner force and displacement of the supporting structure for foundation pit are carried out. There are different losses of prestresses of anchors mostly about 10 %—25 %; and increase of inner axial force of anchors about 10 % during the construction. The inner axial force of steel props increases with the increment of the excavation depth; and its value changes with the varieties of excavation mode

velocity and dismantlement of the underlying props in order. The horizontal displacement of the retaining pile body is related to the pile depth and supporting condition. The deformation of the earth surface is the largest in the middle and the smaller at the end. The calculating data are generally accordant with the measuring data; but there are some differences between them because of the influences of various factors and the dynamic construction.