The invention relates to a molybdenum-based catalyst. The catalyst comprises an active component molybdenum and a carrier, wherein the active component molybdenum exists in the form of molybdenum simple substance and MoOx; wherein 0 < x < = 3. The carrier is a metal oxide, the surface of the carrier is provided with oxygen vacancies, the simple substance Mo in the active component molybdenum is combined with the oxygen vacancies to form a Mo-[O]-M structure, wherein [O] represents the oxygen vacancies and M is a metal element in the carrier; and the active component molybdenum is distributed on the surface of the carrier in a nano-particle shape. The invention further relates to application of the molybdenum-based catalyst or the molybdenum-based catalyst obtained by the preparation methodin oxidation reaction of alcohol and hydrocarbon substances.