Abstract: Functions of the velocity or displacement profiles of slope soil are suggested for describing the slow motiont of natural slopes. Dual or triple piecewise empirical functions are suggested and compared with the field measured results respectively from the shear zone to the rigid zone. Owing to that the slope soil does not rigorously obey the assumption of rigid body, continuous rather piecewise functions of velocity and displacement for the whole soil slope are directly solved from the Newton's equation of motion formulated by Bingham model and compared with the measured results. In conclusion, the two methods for description of slow motion of soil slopes are discussed.