The invention discloses a low-cost deformation magnesium alloy with low anisotropy and a preparing method of the alloy. The alloy comprises, by weight percent, 1.0% to 1.6% of zinc, 0.10% to 0.25% of manganese, 0.10% to 0.26% of copper and the balance magnesium and inevitable impurities. Compared with a developed low-zinc alloy at present, the alloy has the good combination mechanical properties and the low anisotropy, the low-temperature molding property can be obviously improved, and the alloy is particularly suitable for meeting use needs of all boards, rare earth or zirconium is not contained, the alloy cost is greatly reduced, and the alloy is more suitable for being applied in a scaled manner; and the preparing method is used for smelting and casting, alloy components are easily controlled, and the burn-out rate is low.