In this paper, the mechanism of Debris Flow is summarized. The existing methods for Debris Flow monitoring are analyzed and evaluated. A method is presented for monitoring the key factors of Debris Flow based on wireless sensor networks (WSNs). The construction of nodes of WSN, as well as deployment of nodes and energy efficient protocol is introduced as well. WSNs does not only provide the data source for the mechanism exploration of Debris Flow, but also can be established as an infrastructure for Debris Flow forecasting and early warning. Application of WSNs in key factors surveying is conducive to reduction of loss caused by Debris Flow.