Abstract: Taken the Chaozhou and Jieyang area in Guangdong province as an example and based on the analysis of the formation condition of the debris flow,this paper proposes the concept of the potential incompact solid matter and analyzes the formation condition and mechanism of substance source.In particular,this paper discusses the influence of torrential rain,vegetation and human activities to the debris flow.They are the important factors causing the formation of the debris flow source.The viewpoint that solid matter is shortage in this area can be changed.The research results provide a breach for the debris flow research in this area.