The invention discloses a catalyst for preparing a mixed alcohol from synthetic gas as well as a preparation method and application of the catalyst. The invention discloses a catalyst for synthesizing the mixed alcohol through CO hydrogenation; the catalyst comprises a first active component, a second active component and a carrier, wherein the first active component comprises metal cobalt and iron; the second active component comprises cobalt carbide and a cobalt-iron alloy; the carrier is active carbon. The catalyst is prepared from the following components in percentage by mass: 1 percent to 30 percent of the cobalt and 0.1 percent to 10 percent of the iron. The catalyst is prepared by adopting an immersion method; the preparation method is simple and needed catalytic reaction conditions are moderate; the catalyst has the advantages of high catalytic activity and relatively high selectivity of C2 to C18 high-grade alcohols in a product; when the catalyst provided by the invention is used, the alcohol yield of a mixed primary alcohol prepared by the synthetic gas can be improved and the catalyst has good industrial application prospect.