Based on the assumption that the slope bodies are rigid, the dynamic model of the landsiding (forward mod-el) was put forward. According to the dynamic model, the system equations of Kalman filter were constituted. The me-chanical status of a slope was hence combined with the monitoring data by Kalman filter. The model uncertainties or mod-el errors could also be considered through some fictitious observation equations. Different from existed methods, the pre-sented method can make use for not only the statistic information contained in the data but also the information provided by the mechanical and geological aspect of slopes. At last a numerical example was given out to show the feasibility of the method.