Al coating on Mg alloy was prepared by plasma spraying technology, and it was then remelted by laser beam. The change of the coating before and after laser remelting was investigated using SEM, OM, XRD, tensile machine and salt spraying test. The results show that after laser remelting, the mechanical bond between the substrate and the coating changes to metallurgic bond and the adhesion strength is increased from 20.96 MPa to 22.13 MPa. The phase constituent keeps the same. Lots of pores occur in the coating and the porosity ratio is increased from 4.6% to 7.5%. The corrosion time is decreased from 900 h to 264 h.