Mg rich primer-powder topcoat) coating system was first developed and characterized in this research for the corrosion protection of Al alloys. Feasibility of using Mg rich primer (MgRP) as an under layer for powder topcoat was proved through evaluating thermal stability of MgRP, adhesion strength of the (MgRP-powder topcoat) coating systems, and cross-section images of the coating systems. In addition, corrosion protection effects of (MgRP-powder topcoat) coating system were evaluated by exposing samples to accelerated weathering test. Electrochemical impedance spectroscopy (EIS) and visual inspection were conducted during exposure. The results show that (MgRP-powder topcoat) coating systems provided much longer corrosion protection time to Al substrate than the powder topcoat alone. Moreover, gloss measurements indicated that for the coating systems tested in this research, using MgRP as an under layer does not affect the final coating appearance.