Abstract: The experiment was conducted to estimate the drought tolerance of Delphinium grandiflorum seedling stressed by PEG with the concentrations of 0, 5%, 10%, 15%, 20% and 25%, respectively. Different physiology indices including cell membrane permeability, malondialdehyde (MDA), free proline (Pro), peroxidase (POD) activity, superoxide dismutase (SOD) activity and soluble protein were measured. The results showed that the cell membrane permeability, MDA and Pro concentration in seedling leaves of D.grandiflorum increased with drought stress increased. SOD and POD activity increased firstly and then decreased with drought stress increased. Soluble protein concentration had no difference between control and different stress treatments. All of these variation suggested that the seedling of D.grandiflorum had drought tolerance in some degree.