The present invention provides an oxygen carrier for chemical looping hydrogen generation, a preparation method and applications thereof. According to the present invention, the oxygen carrier comprises, by mass, 5-65% of Fe2O3, 5-35% of MoO3 and 30-90% of Al2O3; the oxygen carrier is prepared through a dipping method and can be used for chemical looping hydrogen generation, wherein an alumina carrier is dipped in a soluble solution containing iron and molybdenum, and drying and roasting are performed to prepare the oxygen carrier; molybdenum oxide as the auxiliary agent is added to the oxygencarrier, and the conversion between Mo<6+> and Mo<3+> forms a redox cycle, such that the redox reaction can be promoted, and the reducibility of the active component iron oxide can be easily improved; the dispersity of iron oxide can be improved with molybdenum oxide, such that the particle of the iron oxide can be reduced so as to improve the stability of the oxygen carrier; and the oxygen carrier is suitable for carrying out the reaction at the high temperature, has advantages of good thermal stability, cheap and easily available raw materials and simple preparation method, and is suitablefor industrial applications.