The invention relates to a high-strength heat-resisting wrought magnesium alloy and a preparation method thereof, and belongs to the technical field of nonferrous materials and processing thereof. Thetechnical problem that the high-temperature mechanical property of magnesium alloys in the prior art is poor is solved, and the heat property, the mechanical property and stability of the rare-earthmagnesium alloy are improved. The magnesium alloy comprises 7.0-9.0wt% of Gd, Yb being larger than 0 and smaller than or equal to 4wt%, 1.0-1.5wt% of Zn, 0.4-0.6wt% of Zr and the balance Mg and inevitable impurity elements. The magnesium alloy has high strength and the excellent heat resistance; and through detecting, the property can achieve the conditions that the yield strength under room temperature is larger than 380 MPa and the yield strength under the temperature being 250 DEG C can keep being about 300 MPa. The high-strength heat-resisting wrought magnesium alloy is expected to be usedon force bearing structure components with the service temperature higher than 250 DEG C.