To investigate the differences in drought propagation under various underlying surface conditions in Southwest China, the K-prototypes clustering algorithm was employed to classify the study area into three underlying surface types:the mild karst-agriculture-dominated ecological area, the typical karst-forest and shrub ecological area, and the mild karst-alpine grassland and shrub ecological area. Drought propagation times were quantified using multiple drought indices in combination with the maximum correlation coefficient method, and structural equation model was applied to construct drought propagation chains for different underlying surface types. The results showed that the standardized precipitation evapotranspiration index