Abstract: By applying PEG6000 water stress simulation method, effects of water stress on change of root hydraulic conductance，root system vigor and leaf water saturation deficit were studied. The result indicated: water stress had significant influence on root hydraulic conductivity, root system vigor and water saturation deficit of rubber trees, with the prolongation of the water stress time, root hydraulic conductivity was decreased gradually, but root system vigor increase firstly, and then decreased. According to the decreasing degree of root hydraulic conductivity and root system vigor under water stress and the ability to maintain leaf water, the result showed that, the drought-resistant and adaptive capacity of GT1 was comparatively strong under water stress, followed by PR107, RRIM600 and PB86 orderly.