The invention provides a high-strength magnesium alloy. The high-strength magnesium alloy comprises Zn, Al, Cr, Mn, La, Ce, Nd, Yb, Y, VC, ZrC, WC, TiC, TiB2, ZrB2 and Mg. The invention further provides a die-pressing method of the high-strength magnesium alloy. According to the high-strength magnesium alloy, rare earth elements like La are added in the alloy and have high solubility in the magnesium alloy, the dispersion strengthening effect and the great solution strengthening can both be achieved, besides, the rare earth elements can also have a high bonding effect with impurities elements,such as oxygen, hydrogen, nitrogen, sulfur and iron in a raw material alloy, gas and inclusions in the alloy can be reduced, the form of the inclusions is improved, the inclusions tend to be spheroidized, the inclusions and gas can be removed advantageously, and a melt purifying effect is also achieved; and in addition, the added rare earth elements differ in content, and the synergistic effect of the different rare earth elements greatly improves the strength and corrosion resistance of the magnesium alloy.