AZ91D magnesium alloy and Al metal were bonded successfully at 450 oC with load of 25 or 31 MPa by using Mg-Al eutectic alloy as the solder in atmosphere. The microstructure of the AZ91D/Al joints was characterized by SEM equipped with EDS, and the bond strength was measured through three-point bending test. It was revealed that reactive diffusion occurred obviously at the jointing part. The diffusion layers are composed of α-Mg + β-Mg17Al12, β-Mg17Al12, γ-Mg2Al3 and α-Al. The average bend strength of AZ91D/Al joints is 24 MPa with maximum value 28 MPa. To demonstrate the potential engineering application of this technology, AZ91D magnesium alloy plate was coated with Al foil and its corrosion resistance was tested. Electrochemical test results showed that the corrosion resistance of Al coated AZ91D magnesium alloy plate was greatly improved compared with the uncoated one.