The phenotypic plasticity of plant leaves under drought stress can reveal the ecological significance of plants in different natural environments and understand their adaptive evolution mechanism. Indigofera is the third genus of Leguminosae, and its habitat is diverse and complex, so there are many problems in its classification and evolution. In this study, we chose I. bungeana, which has the widest ecological amplitude and the largest morphological variation in Indigofera. Oneyearold seedlings of I. bungeana from Shimian of Sichuan Province, Mengzi, Yanshan of Yunnan Province were treated with the gradient drought stress. The results were as follows: as the stress of drought was intensified and last, the leaf length and area kept on decreasing, the petiole length appeared much smaller for all three populations of I. bungeana. The density of trichomes on abaxially increased significantly, the length of trichomes on abaxially decreased significantly, the length of trichomes on adaxially change significantly in the populations from Yanshan and Shimian. There was no significant difference on the density of trichomes on adaxially in the populations from Shimian and Mengzi, while the length of trichomes on adaxially did not change in the population from Mengzi. The results of this study can not only provide the evidence for the classification of I. bungeana, but also lay a foundation for the studies on its adaptation and evolution.