The invention discloses a modified lithium manganate material, and a preparation method and application thereof. The modified lithium manganate material adopts a core-shell structure taking LiMn204 as a core and LiMn2-xMxO4-delta as a coating layer, wherein M is one of Al, Ti, Ce, Co and Ni, the value of x ranges from 0.05 to 0.5, and delta ranges from 0.01-0.1. The modified lithium manganate material is prepared by co-precipitation coating, hydro-thermal reaction and high-temperature heat treatment, and used as the cathode material of a lithium ion battery. The preparation process is simple and feasible, the components and the proportion of the raw materials are easy to control, the stability from batch to batch is good, the cost is low, and the synthesized lithium manganate material is high in specific capacity, high in current and excellent in cycle performance, and is expected to be applied in the field of power cells.