The invention relates to a core-shell structure electric catalyst material for lithium air batteries and a preparation method thereof. The electric catalyst material comprises a core layer formed by a transition metal oxide and a shell layer formed by a transition metal nitride, the core layer is a hollow or solid core, the inner diameter of the core layer is 0-50nm, the outer diameter of the core layer is 30-500nm, the thickness of the shell layer is 10-200nm, and the mass of the shell layer accounts for 10-40% of the mass of the electric catalyst material. The preparation method includes that the hollow or solid transition metal oxide is prepared by adopting a liquid phase method. On the basis, transition metal salt is nitrogenized directly to be covered on the surface of the transition metal oxide by adopting a nitriding sintering method, and the core-shell material is prepared by covering the transition metal nitride on the transition metal oxide. The core-shell material has good electrical conductivity and stability, can effectively reduce charging and discharging polarization of the lithium air batteries, reduces internal resistance of the batteries, has good discharging capacity simultaneously, is simple in preparation process method, convenient to operate and low in cost, and achieves large-scale production easily.