Abstract: In order to study the minimum water demand and the tolerance to drought stress of millet seed emergency, PEG solution (with water potential gradient of 0 to - 0.50 MPa) was used in drought stress simulation tests, the change of seed germination ability and the minimum water demand of‘Datong 34’were studied. The results showed that seed germination ability was inhibited through the restriction of available water assimilation, the germination potential decreased with the increase of osmotic potential, which were mainly shown as the accumulated germination rate, water absorption rate and germination stress index decreased with the increase of stress strength, while the radical bud ratio increased. Under the treatment of -0.5 MPa PEG 6000, the difference of drought tolerance index was the most significant, so this concentration could be used in the identification of drought tolerance of millet.