In this study, we used wild type of Arabidopsis thaliana as tested materials, and the CmSAMDC gene from melon was built into the pCAMBIA1304 binary vector, then the vector was transformed into A. thaliana by using Agrobacteriummediated method. The transgenic plants overexpressing CmSAMDC were obtained by screened on MS medium containing 50 mg/L hygromycin, and then the salt tolerance test was performed by T₃ transgenic seedlings. The results showed that: (1) the plant overexpression vector 35S∷CmSAMDC was successfully constructed and finally the T₃ transgenic A. thaliana plants were obtained after transformed by Agrobacterium and resistance screened by hygromycin. (2) The lateral roots of the transgenic T3 lines were stronger than that of wildtype under 100, 150 and 200 mmol/L NaCl treatment. Meanwhile, the transgenic T₃ lines grew up normally under 200 mmol/L NaCl treatment by irrigating roots, while the wild type plants were significantly inhibited under the same condition. In addition, the T₃ transgenic seedlings were still alive under 400 mmol/L NaCl treatment by irrigating roots 16 days later whereas the wildtype plants gradually died. Furthermore, the level of MDA was higher in wildtype plants than that of transgenic plants under the same salt stress. The results showed that overexpressing of CmSAMDC gene could obviously enhance the salt tolerance of transgenic A. thaliana.