The invention relates to a coating technology, in particular to a Cr-O-N activated diffusion impervious layer. An arc ion plating technology is adopted, pure chrome is used as target material, the impervious layer which can effectively reduce the mutual diffusion of metal elements between a coating and a high-temperature alloy matrix under high-temperature oxidation conditions through controlling the flow quantity of O2 and N2 during the reaction process; a MCrAlY coating is deposited on the impervious layer to be used as an oxidation resistant coating. The referred Cr-O-N activated diffusion impervious layer has compact structure, combines well with the matrix, has simple and low preparation cost, and is a good diffusion impervious layer. The Cr-O-N activated diffusion impervious layer is applied to the matrixes that are nickel-base, cobalt-base or ferrum-base high-temperature alloys.