Abstract: In order to screen excellent plant materials suitable for ecological restoration in northern cold quarry,three alfalfa seeds（Medicago sativa,Medicago falcate,Medicago ruthenica）were treated with different concentrations of PEG-6000（0%,5%,10%,15%and 20%）to verify their drought resistance.The results showed that under 5%-15% PEG-6000 simulated drought stress environment,the seed germination potential and germination potential of three alfalfa species did not decrease significantly,but under 5% PEG-6000 treatment,the seed germination rate of Medicago falcate and Medicago ruthenica increased,while under 20% PEG-6000 treatment,the seed germination rate and germination rate of three alfalfa species decreased significantly,and the order of drought resistance was Medicago ruthenica＞Medicago falcate＞Medicago sativa.