In order to analyze the motion characteristic of clay landslide, the circular sliding surface is defined as the most dangerous slip plane according to clay landslide characteristic. Base on the assumption that landslide moves as a group of particles motion, the physical motion model of landslide failure is established. Base on function transformation relations, in the process of landslide movement the forecast formula of landslide distance is deduced. Kinetic parameters such as motion acceleration velocity, sliding distance are obtained by calculation. Compared with the sled model, this method can be used for landslide case. The case results show that the motion acceleration of homogeneous clay landslide approaches to its maximum immediately in a very short time, and then reduces gradually. Landslide movement speed increases rapidly in the initial stage, then slows down gradually until the landslide movement stops. The final horizontal sliding distance of this method is equal to the result calculated by the sled model approximately, and the relative error is only 1.2%, which is very small.