Considering the nonlinear and dynamic characteristics of settlement deformation, a global piecewise nonlinear analysis model of settlement deformation is proposed based on the modified M5′-principal component(M5′-PCR)model tree, to analyze the settlement process by selecting the influence factors with correlation analysis and reducing the dimension of high dimensional influence factors with principal component analysis method. The the improved M5′-PCR model tree is verified by comparing with the measured settlement. By comparing the prediction results of improved M5′-PCR model tree, M5′ model tree, multiple linear regression, and principal component regression analysis model through the absolute difference and the root mean square error, the results show that improved M5′-PCR model tree has a higher precision in settlement prediction and provides a new approach for the analysis of dam settlement deformation.