In order to explore the adaptability of Melilotus Mill to low temperature environment, the wild M.albus and M. officinalis ollected from Dazi, Tibet were used as experimental materials to explore the seed germination characteristics of their seeds under -4 ℃ low temperature stress , Measured the malondialdehyde (MDA) content, soluble sugar (SS) content, free proline (Pro) content, superoxide dismutase activity and peroxidase of seedlings under -10 ℃ ～ 5 ℃ low temperature stress (POD) Changes in activity, and a comprehensive evaluation of cold resistance using the membership function method. The results show that: -4 ℃ low temperature stress has a significant inhibitory effect on the seed germination of the two materials; as the temperature decreases, the MDA content in the leaves of the two materials continues to increase, and other physiological indicators show a trend of first increasing and then decreasing, both The peak value is reached at -5 ℃; the comprehensive evaluation results of the membership function method show that the cold resistance of M.albus is higher than that of M.officinalis. This study will have important reference significance for revealing the adaptation mechanism of wild Melilotus Mill in Tibet to low temperature environment and the development and utilization of local Melilotus Mill germplasm resources