The invention provides an oxygen carrier for chemical looping dry gas reforming, and a preparation method and application of the oxygen carrier. The oxygen carrier is a composite metal oxide adopting a hexaaluminate structure, and has the general formula of AMxAl(12-x)O19, wherein A is rare earth metal lanthanum and / or barium, M is transition metal Fe, and x is greater than 0 or smaller than 5. The temperature of the oxygen carrier in a fuel reactor is 750-1000 DEG C, and the temperature of the oxygen carrier in an oxidation reactor is 750-1000 DEG C, and both of the reaction pressures are normal pressure. The preparation method comprises the following steps: using iron nitrate, aluminum nitrate, lanthanum nitrate and / or barium nitrate as a precursor to prepare a nitrate solution; adding ammonium carbonate as a precipitant for coprecipitation; performing suction filtration, washing, drying and roasting to obtain the oxygen carrier. The oxygen carrier has the advantages of being larger in oxygen-carrying rate, higher in reactivity, excellent in shock-resistant mechanical property and high temperature stability, environmental-friendly, low in cost and easy to prepare.