In order to define settlement deformation feature of ground surface caused by deep pit excavation of subway, refering to the construction process,data monitored of deep pit in D city subway station is analyzed. It is concluded that common ground subsidence deformation characteristics of deep foundation pit. At the same time,in order to forecast the settlement of two typical points of monitoring data,we used the grey GM(1,1)model according to different construction stages. Prediction results show that the gr...