The soil and water loss in the source of the yangtze river is paied attention gradually inrecent years, It is not only widespread in whole watershed but also very serious in parts. Mud-rockflow is the common serious erosion form and has some special erosion characteristics,so it is neces-sary to adopt some special measures to control it.Through the investigation to the cause of mud-rock flow in the Menzonggou wathershed inyushu county of Qinghai province. it is considered thatthe main causes are not only geology、landform、soil、rainfall、vegetation and mankind factor but alsomelting erosion and rainfall forms. According to the danger and characteristics of the mud-rockflows in this watershed ,the comprehensive control system for controlling gullies in combination withcontrolling slopland is put out to decrece the disasters to least.