Abstract: The destroy of surrounding ground settlement caused by foundation pit dewatering has attracted wide attention.The traditional calculation method of ground settlement was based on the view of unchangeable total stress.Calculating the increment of effective stress and neglecting the increment of effective stress caused by seepage will easily cause the big error.So,based on the condition of changeable total stress and seepage,this paper gives out the calculation formula of soil layer increment of effective stress to meet the calculation requirement of surrounding ground settlement caused by foundation pit dewatering.