Abstract: The effects of water stress on several physiobiochemical indexes of Chamaecrista rotundifolia under PEG-6000treatment were studied in a series laboratory tests.The results showed that the RWC was decreased, the content of Chl and osmotic adjustment matter were raised, the activity of SOD and POD were increased, meanwhile, the cell membrane systems of mulberry were damaged and osmotic capability was boosted, relative electric conductivity and MDA content were increased along with the increasing of water stress.Furthermore, along with the time prolonged of water stress, the activity of POD was increased at first and then decreased, demonstrated that the activity of cell protective enzymes was increased under drought stress, but then decreased with the heavier stress to exceed the endurance for Chamaecrista rotundifolia.