The invention belongs to the technical field of lithium ion battery materials, and discloses a fast ionic conductor coated lithium-transition metal oxide material having a chemical formula of (1−x)Li1+a (Ni(1−m−n)ConMnm) 1−bMbO2·xLicAldTieM′fM″g (PO4)3 and a preparation method thereof. The fast ionic conductor coated lithium-transition metal oxide material of the present invention has lower impedance, excellent cycle performance and safety performance under high voltage, especially when the charging voltage is greater than 4.62V, 4.65V, or higher. The Lithium-transition metal oxide can be obtained by a primary calcination, and the final product of lithium-transition metal oxide material coated with fast ionic conductor can be obtained by a secondary calcination.