Based on the formation of debris-flow dam, outburst mechanism, the main features and disaster process, the authors chose the high way from Ranwu to Peilong in Tibet to be study area. The Guangxieco Lake is a typical outburst lake, and Midui Gully is its downstream gully. The region was investigated many times and chose to be the early-warning point. In this paper, an early warning system and supporting technology for debris flow caused by glacier lake outburst is proposed depending on the main principle of glacier-lake outburst prevention.