Abstract: Enhanced ultraviolet radiation induced by human activities widely influenced plant adaptation, which accompanied with drought stress severely reduced crop yields. In the current study, two alfalfa (Medicago sativa) cultivars with different drought resistances, Aohan (high resistance) and Sanditi (low resistance), were used to analyze the responses of leaf cuticular wax content and crystal structure, leaf water potential (LWP), and ultraviolet absorbing compounds under soil water deficit and enhanced ultraviolet radiation (UVR) stresses. The results showed that the leaf wax content in Aohan was significantly higher than that in Sanditi. Compared to well-watered plants, leaf wax content and LWP in Aohan with combined treatments of UVR and soil water deficit increased, while LWP in Sanditi changed insignificantly. This indicates that high-drought resistant cultivar might maintain higher level of LWP to control water loss by increasing wax deposition on leaf surface. Under the conditions of 0.05 W/m² UVR dose or combined treatments of UVR and soil water deficit, the platelet wax crystalloid on leaf surface of both alfalfa cultivars melted, which increased covering areas and UVR reflection rate, and thus would reduce cuticular water loss. Under 0.1 W/m² UVR dose, some crystal platelets paralleling leaf surface while vertically distributing above other crystalloid, appeared on leaf surface of Aohan, which efficiently reduced the effect of UVR on plant physiology, while the wax crystalloids of Sanditi further melted. The structure of wax crystalloids had no significant response to solely water deficit treatment. The contents of ultraviolet absorbing compounds had no significant response to enhanced UVR, indicating that the wax crystalloid structure on alfalfa leaf surface had direct defense mechanism to UVR, which partly might delay or replace the defense mechanisms from secondary metabolic compound such as ultraviolet absorbing compounds.