Combined with engineering experience,make a summary to influencing factors about foundation settlement of existing buildings caused by foundation pit dewatering.Aimed at the problem that compressibility in additional stress segment can not be accurately taken in estimating foundation settlement caused by foundation pit dewatering by layer-wise method, propose the method based on formation stress history to estimate foundation settlement caused by foundation pit dewatering,while combining with engineering example,make a prediction for composite foundation settlement caused by foundation pit dewatering.