The HAL1 gene cloned from yeast was introduced into alfalfa cultivar ‘Longmu 803’ em-bryo cellus.After screened by 2 mg/L of Basta and PCR,the HAL1 gene was proved inserted into the host genome and 11 transgenic plantlets were obtained.A salt-tolerance evaluation was carried out and the re-sult showed that the untransgenic plants could not root on the medium MSO with a concentration of NaCl higher than 0.6% and died gradually.Contrasted with the untransgenic plants,the transgenic plants could root in the medium with a concentration around 0.6% to 1.2% of NaCl and grew normally.This indicated that the HAL1 expressed in alfalfa and improved the salt-tolerance of alfalfa.