Methanol steam reforming (MSR) is an attractive approach to produce hydrogen for fuel cells. Due to the limited catalyst loading volume and frequent start-ups and shut-downs on board, it is highly desired to develop an extremely active and robust catalyst. Herein, on the basis of industrial Cu/ZnO/Al2O3 catalysts, a series of CuZnAl-xMg catalysts with enhanced Cu-ZnO synergy were synthesized via magnesium assisted strategy. The incorporation of magnesium was found to be beneficial to the enhancement of catalytic activity and stability of catalyst. A combination of complementary characterizations (e.g. XRD, H2-TPR, N2O chemisorption, TEM, XPS analysis etc.) proves that isomorphous substitution of Cu2+ in malachite phase gives rise to more dispersive Cu and ZnO NPs, and the increased Cu+/Cu0 ratio indicates the strengthened Cu-ZnO synergy effect, which leads to the boosted stability during the thermal treatment.