Abstract: Wangmo river valley in Guizhou province Wangmo county has complicated geological conditions and high topography fall,strong confluence,rich loose material and three main gullies. On the condition of strong rainfall,small debris-flows developed in channels can break out simultaneously and flow into the main gully,finally gather together in Wangmo river. The increased flow and sediment can easily induce great debris flow disaster,which means a great loss of life and property to the river dwellers and the downriver Wangmo County. A great debris flow disaster happened on Jun.6th,2006,which caused great loss to local residents. Based on field research,an automatic monitoring and warning system is constructed to decrease the harm. The system contains many functions including data collection,interpretation,transmission,analysis,decision,control and warning. The monitoring contents conclude rainfall,infrasound,water level and image. The field monitoring system is composed of rain gauge,level meter,infrasound alarm apparatus and video device. Thus warning threshold values and warning levels are drawn up on the basis of field research and data analysis. By data analysis,it is found the automation system can make effectively real-time dynamic monitoring and early warning of Wangmo river debris flow in Wangmo county,Guizhou province.