The high temperature oxidation resistance behavior of atmospheric plasma sprayed CoNiCrAlY coating with a thin layer of Cr2O3 employing chromate treatment was investigated. The high-temperature oxidation test was performed at 1423K for 7.2, 14.4 and 32.4ks, respectively. The formation of the oxide layer on the CoNiCrAlY coatings with Cr2O3 thin layer by chromate treatment was compared with that of the non-Cr2O3 thin layer. The oxide layer formed on the both types of MCrAlY coatings grows with increasing the elevated temperature and the holding time. Also, the thickness of the oxide layers was proportional to the square root of time. The thickness of the oxide layer on CoNiCrAlY coatings with the thin layer of Cr2O3 was only 60% as compared with that of the non-Cr2O3 thin layer in high temperature oxidation tests at 1423K.