本文以极具典型的平川泥石流为例比较全面的分析了冲淤变动型泥石流的物源问题 .根据现场调研及室内岩土分析进行的研究成果显示 ,川西南高山深谷地区的大型泥石流沟中的松散土体以中、粗粒段为主 ,其分布与地形密切相关 ;位于泥石流沟中、前部位的松散土体的稳定性最差 ,是补给泥石流的重要物源 ;松散土体的发育主要受控于地质及岩土环境 ,人类活动只能影响松散土体的稳定性 In this paper, the typical Pingchuan debris flow is taken as an example to comprehensively analyze the source of erosion and depositional debris flow.According to the field investigation and indoor geotechnical analysis, the results show that in the large debris flow ditch Loose soil is dominated by medium and coarse segments, and its distribution is closely related to the terrain. The loose soil located in the front of the debris flow channel is the least stable and is the most important source of debris flow. The development of loose soil mainly Under the control of geology and geotechnical environment, human activities can only affect the stability of loose soil