The physiological indes of seed germination and seedling growth of Cassia alata L. after PEG treatment were tested. The result showed that all different quality concentrations of PEG treatments reduced the germination percentage，and the restriction efficiency increased with the increasing of concentration. The cultivation tests of seedlings in PEG solutions of different quality concentrations showed that the membrane permeability and malonaldehyde content increased with the increasing of PEG concentration, however, the chlorophyll content of the seeding leaves increased at first but then decreased，while the Pn decreased.