The invention relates to the technical field of magnesium alloy preparation, in particular to a high-performance magnesium alloy. The high-performance magnesium alloy comprises, by weight, 0.28%-0.36%of Bi, 0.51%-0.83% of Ca, 5.05%-8.23% of Si, 1.62%-1.95% of Sn, 0.1%-0.3% of Zn, 0.05%-0.09% of Na, 0.07%-0.12% of K, 0.26%-0.44% of Ni, 0.06%-0.18% of Cu, 1.2%-1.4% of Ti, 0.24%-0.36% of B and the balance magnesium. The invention further discloses a preparation method of the high-performance magnesium alloy. The magnesium alloy has the good corrosion resistance and high-temperature creep resistance, the defect that the ignition point is low is overcome, and the mechanical property of the magnesium alloy is improved.