The invention relates to a low-cost high-compression-strength wrought magnesium alloy and a preparation method thereof. The magnesium alloy material is composed of six elements, namely Mg, Zn, Mn, Sn,Ca and Cu, wherein the content of the Zn element is 4.0%-8.5%, the content of the Mn element is 0.1%-0.4%, the content of the Sn element is 0.1%-0.4%, the content of the Ca element is 0.1%-0.4%, thecontent of the Cu element is 0.1%-0.4%, the content of inevitable impurities is less than or equal to 0.15%, and the balance is the Mg; and compared with a traditional commercial grade magnesium alloymaterial, high compressive yield strength can be obtained after the magnesium alloy material is subjected to a conventional extrusion treatment, and the compressive yield strength of the alloy is obviously higher than tensile yield strength. The magnesium alloy material does not contain precious alloy elements, and is simple in preparation process and low in cost, has very important practical value for manufacturing a pressed magnesium alloy component.