Assuming that road slope and landslide object are rigid, the landslides moving displacement was drawn based on their geometry shapes and the physi-mechanical features of materials, and the dynamic model of landslide was also set up, then DDOD(double difference observation data) was combined with the deformed monitoring point and the carrier phase observation data on base point, which can be used to monitor the landslides deformation rule from horizontal, vertical and directional view simultaneously. Observing equation was set up, which sufficiently reflects the activities of landslide in entire directions. Filter model includes some information such as mechanical state and GPS observing data by Kalman filter.