Abstract: In order to understand the effect of UV-B radiation on systematic water metabolism in plants, this review outlined domestic and international achievements in the last 30 years relating to the physiology and biochemistry of plants under UV-B radiation, such as root activity, transpiration rate, water use efficiency, and changes in leaf proline and soluble sugar content at different plant developmental stages. The effect of UV-B radiation on stomatal behavior and related mechanisms including a variety of signal molecule (ABA, hydrogen peroxide, nitric oxide, etc.) content and the role of signal molecules in stomatal activity were also reviewed. We conclude that UV-B radiation damage to plant water metabolism (that is associated with species, developmental stage) is proportional to the UV-B radiation dose and treatment time. Studies on UV-B radiation in water metabolism are vital for preventing UV-B radiation stress in plants under natural and agricultural production environment.