Abstract: This paper first introduces three basic models——the ARMA model, the AR model and the MA model in the time series analysis and their statistical properties. Taking the absolute displacements of a large dam in the western of China as an example, the paper puts the emphasis on the procedure of the establishment of the model for deformation analysis of the large dam, An AR(2) model has been built and used in the prediction of deformations.The result shows good prediction accuracy. Compared with the stepwise regression analysis, it is of better accuracy. Therefore, if the regression factors have not been observed, the method mentioned in this paper will show its advantages in deformation. analysis.