Abstract: Dewatering for foundation pit excavation is usually used. This method can change the engineering properties of soils around the pit. Consequently, the buildings around the pit can be affected. Differential settlements and cracking in the buildings can occur. Dewatering at the pit of the West Railway Station in Jinan made significant effects to subgrade of the Beijing-Shanghai High-Speed Railway Line. This paper examines this problem. The effect of dewatering at the large station pit to its surroundings is not yet fully understood theoretically. This paper studies the effect of the foundation pit to the nearby composite foundation settlement. It uses the section DIK419+250 Jinan West Railway Station. Settlement plates are used to monitor the settlement of the subgrade surface. Settlement devices at different ground depths are used to monitor the settlement of the subgrade at depths. The cross-sectional profile device is used to monitor the changes along the cross profile of the subgrade. The monitored results are used to examine the effects of the dewatering on the subgrade surface, its depth soils and its cross profiles. Furthermore, according to the site conditions, the paper uses the finite element analysis method to numerically simulate the on-site monitored results. The comparative studies have the following conclusions: (1)the improvement of the composite foundation can reduce the effect of the dewatering; (2)the area with variable pile foundation lengths can be largely affected by the dewatering; and (3)pit dewatering can have larger effect to the subgrade settlement than the sub-soils.