Abstract: Foundation settlement prediction is a significant task of rock and soil stability study.Based on the existed models of settlement prediction,a new foundation settlement model and its solution method-constrained optimization are put forward.This method is simple,rapid and accurate.The effect of measured point number and its stage to prediction accuracy is discussed.The more the measured point number is,the better the result predicted is.The result predicted is generally less when the measured point is at initial stage while it is larger at developing stage.The result is related with the characteristic of the model and project.As soon as the point reaches the terminal stage,the result predicted accords with the actual condition.Resultsshow that the prediction result of the new model is more accurate than that of Deng Ying-er model and Gompertz model.