This invention relates to a method of preparing a mixed manganese ferrite coated catalyst, and a method of preparing 1,3-butadiene using the same, and more particularly, to a method of preparing a catalyst by coating a support with mixed manganese ferrite obtained by co-precipitation at 10˜40° C. using a binder and to a method of preparing 1,3-butadiene using oxidative dehydrogenation of a crude C4 mixture containing n-butene and n-butane in the presence of the prepared catalyst. This mixed manganese ferrite coated catalyst has a simple synthetic process, and facilitates control of the generation of heat upon oxidative dehydrogenation and is very highly active in the dehydrogenation of n-butene.