Construction of a food-grade expression vector for application to lactic acid bacteria (LAB) is of importance for dairy fermentation system. Anα-galactosidase (aga) gene encoding an enzyme degrading melibiose was ampliifed by PCR from the plasmid pRAF800 of Lactococcus lactis NZ9000. The aga gene was introduced into pMG36e to substitute the primary antibiotic selectable marker of pMG36e, resulting in construction of a new food-grade expression vector pMG36-aga. To testify the expression efifciency of exogenous gene in pMG36-aga, a 1.5 kb longα-amylase (amy) gene from Bacillus licheniformis was cloned by PCR and introduced into the plasmid pMG36-aga. The resultant plasimd pMG36-aga-amy was transformed into L. lactis ML23 by electroporation. The positive clones were selected with the medium containing melibiose as the sole carbon source. The selection efifciency of aga was 8.71×103 CFU with a standard deviation of 9.1×102 CFU mg-1 DNA of pMG36-aga. Furthermore, the SDS-PAGE analysis showed that the pMG36-aga-amy expressed a 56.4 kDa protein which was the same as the putative molecular weight ofα-amylase. The starch plate assay also indicated that L. lactis ML23 displayed high activity ofα-amylase by expressing of amy gene of pMG36-aga-amy.