While studying the dynamics of landslides one of the main tasks is the organization of geodetic observations for network traffic landslide points established on the surface of the landslides, and, in the end obtaining the vectors of displacement and velocity of displacement of landslides. But since in different parts of the body of the landslide happen skew, geodetic landslide the network will be irregular deformations and in this situation the most important task is to determine the main axes of movement of the landslide. Methods for determination of the private vectors of displacement and full displacement vector in the plane, based on a gradient approach. These methods give a clear idea about the main axis of movement of the landslide point, however, there is no information about the resultant axis of movement of a landslide in General. In the present work examines the construction of root-mean-square displacement ellipsoids of landslides on the basis of geodetic monitoring. Using a probabilistic approach, the equation of the surface of the ellipsoid with randomly oriented in space of the principal axes. The obtained cubic equation with three real roots to determine in the General case the principal axes (A, B, C) mean square displacement ellipsoid of the landslide. As a result of solving this equation the formulas for calculating the parameters of the mean-square displacement ellipsoid of the landslide. Knowing the parameters of the ellipsoid, one can obtain the mean square displacement of a landslide in General.