为了探明火烧后泥石流在不同时间点的易发性，选择2020年3月在经久乡泸山发生严重火灾的火烧迹地作为示范研究区，以“空间换时间”的思想为基础贯彻整个研究，通过室内实验，获取了研究区在火后不同时间的根土力学参数。利用获得的实验参数，通过坡体失稳模型，得到火后不同年限的坡体失稳系数，根据坡体稳定性划分标准，得到了火烧后不同年份的坡体失稳面积，最终提炼出火后不同年份的物源强度指标。以物源强度作为动态评价指标，以地形地貌指标作为静态评价指标，构成了小流域尺度下的火后泥石流易发性动态评价指标体系。选用熵权法计算指标因子的权重结合综合指数法，对经久乡泸山火烧迹地进行了动态的泥石流易发性评估。依据结果，对火烧后多年依然高易发的流域以及短时间内高易发的流域进行针对性整治，既能够有效地预防和减少泥石流的发生概率，又能节约经济成本，做到真正意义上有效的防灾减灾。

In order to find out the susceptibility of debris flow after fire at different time points, the burned land where a serious fire occurred in Lushan Mountain, Changshou Township in March 2020 was selected as a demonstration research area. Based on the idea of "space for time", the whole study was carried out. Through laboratory experiments, the root soil mechanical parameters of the study area at different time after fire were obtained. By using the experimental parameters obtained, the slope instability coefficient of different years after fire was obtained through the slope instability model. According to the slope stability division standard, the slope instability area of different years after fire was obtained. Finally, the source strength indexes of different years after fire were extracted. The dynamic evaluation index system of post-fire debris flow susceptibility at small watershed scale was established by taking source strength as static evaluation index and topographic and geomorphic index as static evaluation index. Using the entropy weight method to calculate the weight of index factors combined with the comprehensive index method, the dynamic susceptibility assessment of debris flow was carried out on the burned land of Lushan Mountain in Changshou Township. Based on the results, targeted remediation of watersheds that remain highly susceptible for many years after a fire and those that are highly susceptible within a short period of time can effectively prevent and reduce the probability of mud slides, while also saving economic costs and achieving truly effective disaster prevention and mitigation.