Great effects have been achieved since 1991 when the landslide and debris flow early-warning system in the control areas of siol and water loss in the upper reaches of the Yangtze River was established.Construction process and operation mode of the system are introduced.Effects of the system are evaluated according to economic,social,and ecological effects it brings.Economical effect is evaluated according to protection ratio and loss ratio of investment.To protection ratio,land protection ratio is 15.11 km2 per 104 yuan and resident life protection ratio is 40.0 persons per 104 yuan.Moreover,fixed assets protection ratio is from 40.0 to 93.3.To loss ratio of investment,economical loss ratio is 3.63 and casualty loss ratio is 5.69 persons per 104 yuan.Correlative evaluating data and instances show that the achieved effects of the system are remarkable and its construction and development should be further enhanced.