Abstract: In this paper,the authors explored the fractal features of debris flow accumulations,moraine accumulations,alluvial accumulations and residual accumulations at Peilong section along Sichuan-Tibet Highway.According to the fragmentation model and grain size analysis,grain-size fractal dimension were calculated for different types of accumulations.The results showed that fractal dimensions vary for accumulation: the debris flow accumulation with the greatest fractal dimension,the moraine accumulation with the second,residual accumulation with the third,and the alluvial accumulation with the smallest.At the end of the paper,geological significance of grain-size fractal dimension of accumulations was discussed in detail.The grain-size fractal dimension of accumulations reflects the complexity and self-organization property of accumulation,forming process,history of accumulation,and the carrying capacity of the dynamic process,such as debris flow,glacier,river,flood,and so on.Therefore,it can be used as an indictor for classification of accumulations and identification of their origins.This new method is anticipated to provide a better insight into origins of accumulations,which in turn could help gain a better understanding of engineering geological behaviors.