Abstract: In order to understand and master the physiological response to water stress and its effect on sorghum yield traits,two factors and four levels of a randomized block design was studied.The results showed that activities of SOD and POD could be improved and contents of Pro and MDA could be increased under mild water stress.Under moderate to severe water stress activities of SOD and POD decreased and contents of Pro and MDA increased.After rehydration Seedling Stress,four physiological parameters basically could be restored to its original state,except the long duration of severe stress treatment, and yield traits significantly higher than the control under moderate long duration and short duration of severe stress,5% of the difference was significant.After re-jointing of water stress,four physiological parameters could be restored to the original level under the short duration of Stress, and there was no significant effect on yield traits. Under the long duration of stress, physiological parameters was not restored to its original state, yield traits fell significantly worse with stress, and reached significant or extremely significant level.