In view of the disadvantage of low precision in the traditional method in which Kalman filter is used to deal with the deformation data of the object and in the light of the theory that Kalman smoothing has a higher precision than its filtering

the problem of the landslide deformation estimation is viewed as not only the Kalman filters problem but also the Kalman smoothers problem in this article. The Kalman smoother is used to deal with the monitoring data of the landslide displacement in order to highly improve the precision of the prediction of landslide

and then a fixed interval smoothing algorithm is given based on the prior study. At last the example of the Longxi landslide in Longyangxia is taken and analyzed

and the analysis of the instance result indicates that the method proposed in the article is feasible and efficient. In the part of the conclusion

the corresponding suggestions are proposed in view of the problem existing in the actual applications.