Abstract: The annual seedlings of Photinia fraseri were treated with four treatments including normal water supply (75%~80% of soil maximum moisture capacity), mild stress (55%~60%), moderate stress(40%~45%) and severe stress(30%~35%). Through pot experiment, studies were made of the effects of water stress on membrane permeability, MDA content, net photosynthetic rate, transpiration rate, root growth characteristics and activity. The results showed that the degree and time of water stress had certain relativity with membrane permeability. Among control, mild stress and moderate stress, the difference was not significant. Along with the aggravation of stress degree, MDA content would rise and reach the peak in 20^th day, then maintain a stable state. Water stress and photosynthetic rate had positive correlation, and the net photosynthetic rate maintained a high level in a long period. But the transpiration rate presented unimodal curve with rising and then descending, the change of severe stress treatment was not significant, and the downtrend was not obvious. Water stress could inhibit the main root growth with the branch root growing, the order of growth quantities was severe stress > moderate stress > mild stress> the control. The intensification of water stress could reduce the number of branch root, but the degree of water stress was negatively related to root absorption area and root activity. The treatment of severe stress had a significant difference with the others, the treatments of moderate stress and mild stress had not significant difference with the control. The analyses above indicated that Photinia fraseri had strong tolerance to water stress.