MgFe-layered double hydroxides (LDHs) were prepared by co-precipitation method with the ratios of [Mg2+]/[Fe3+] varied in the range of 2:1-6:1, and occupied as heterogeneous catalysts for the degradation of Methylene Blue (MB) in the Fenton process. MgFe-LDH prepared with the ratio of [Mg2+]/[Fe3+] at 3:1 was verified to be of high purity. The Fenton-like process catalyzed by MgFe-LDH performed excellently, and more than 97% degradation of MB was obtained with 0.5 mmol/L H2O2 and 0.50 g/L MgFe-LDH at initial pH 2 at room temperature. The occurrence of hydroxyl radicals (·OH) was detected and the mechanism was proposed. MgFe-LDH is of excellent catalytic activity and good reusability.