Abstract: In this study,the effects of different drought stress environments on bud of seeds,protective enzyme activity of seedlings and water content of seedling leaves of three varieties of alfalfa widely cultivated in Northwest China,including Medicago varia cv.Gannong No.1,Medicago sativa cv.Amerigraze401+Z,and Medicago sativa cv.Xinjiang Daye,were assessed under an artificially simulated osmotic stress condition prepared with polyethylene glycol(PEG-6000).The results showed that with the elevation of PEG-6000 concentrations(5%-25%),the bud of seeds,protective enzyme activity of seedlings and water content of seedlings leaves of the three tested varieties of alfalfa were affected in varying degrees.The germination rate,germination index,vigor index and germination potential of the three tested varieties of alfalfa were found obviously reduced,the water content of seedling leaves had no significant changes,and the changing features of the protective enzymes activity of seedlings were different.The membership function analysis demonstrated that the descending order of the drought resistance in the seed germination period of the three tested varieties of alfalfa was Medicago varia cv.Gannong No.1,Medicago sativa cv.Xinjiang Daye,and Medicago sativa cv.Amerigraze401+Z.According to the mean value of comprehensive evaluation,the alfalfa varieties of Medicago varia cv.Gannong No.1 and Medicago sativa cv.Xinjiang Daye had stronger drought resistance than Medicago sativa cv.Amerigraze401+Z.