The mountain area in the east part of Liaoning province is one of the prority areas with mud-rook flow distributed in China. This paper deals with the basic conditions of mud-rock flow in this region and suggests that the heavy rain is the main factor causing mud-rock flow formation in this region. Physical weathering and rift structure are the important process to form the loose solid materials in mud-rock flow. Rock properties and vegetation cover have an important effect upon mudrock flow. Finally, this paper points out that the engineering practices in the immediate future and the biological measures including forests and vegetation covers in the distance future are the principles of controlling mud-rock flow in the mountain areas in the east part of Liaoning province