Abstract: The salt tolerance of Medicago sativa cv. Zhaodong and M. sativa cv. Nongjing No.1 and their physiological responses under salt stress were studied in seedlings cultured in 1/2 Hogland solution supplied with NaCl at concentrations of 0, 50, 100, 200, 300 or 400 mmol/L. Salt injury was measured after the treatment. The content of malondialdehyde (MDA), chlorophyll, proline before and after 3, 6, 9, 12, 15 and 21 days of salt stress were measured and analyzed. The salt tolerance of the two species was comprehensively evaluated by fuzzy subordinate function. There was no significant effect on the growth of two M. sativa at low concentrations of NaCl, showing they had a certain salt tolerance ability. The content of MDA increased with an increase of NaCl concentration. While under the stress of 200 and 300 mmol/L, the content of MDA increased initially then decreased, and then increased again after a prolonged time. With the concentration and duration of NaCl stress increasing, salt injury increased, the content of chlorophyll reduced, and the proline content was considerably increased. However, the accumulation of proline was not entirely consistent with salt-tolerant performance. The results of a comprehensive evaluation showed that the salt tolerance of M. sativa cv. Nongjing No.1 was higher than that of M. sativa cv. Zhaodong under the stress of 100 and 200 mmol/L NaCl, while under the treatment of 300 and 400 mmol/L, the salt tolerance of M. sativa cv. Zhaodong was higher than that of M. sativa cv. Nongjing No.1.