Abstract: To reserch the effects of salt stress on the alfalfa in the germination,15 alfalfa varieties were carried out by NaCl stress at different concentrations, by comparing the germination potential, relative germination potential, germination rates, relative germination rates and the strength of roots, stems, and seedlings at different salt concentrations, the results showed: the most varieties (13/15) can keep higher germination abilities (89% or more); However, when the salt concentration reached 0.8%, the germination ability of each variety was quite different. At the same time, abnormal seedlings began to appear, which was the optimum starting point concentration for the identification on salt stress (NaCl ) during the germination period of alfalfa.The stronger the salt tolerance, the less proportions of abnormal seedlings appeared. The toxic effected more seriously with the salt concentration increasing,the more roots of germinating seedlings wre inactivated.Although the roots of the longer seedlings were inactivated, A few of seedlings can sprout new roots to increase the salt-tolerance of alfalfa germplasm resources. By clustering analysis, the results showed that the varieties with strong salt tolerance were: ‘Rock’, ‘Zhongmu NO.1’, ‘Longdong’, ‘Zhongmu NO.3’ and ‘DS310FY’.All of these provides theoretical support for the rapid screening, introdcing and cultivating of salty alfalfa varieties in saline-alkali areas.