Effects of drought stress on the seed germination and physiological characteristics of amaranth were investigated. The results were as follows: the germination rate and germination potential of amaranth decreased with the increasing of PEG-6000 concentrations. Meanwhile, the root length, shoot length and peroxidase (POD) activity were significantly increased at lower PEG-6000 concentrations, but then decreased with the increasing of PEG-6000. Malondialdehyde (MDA) content, proline content and superoxide dismutase (SOD) activity were all significantly increased under drought stress, and reached the top at 20% PEG-6000. These findings indicated that amaranth tolerates drought stress through increasing the activities of SOD and POD and accumulating proline content.