NiCoCrAlYTa coating has been widely used as an antioxidant coating for hightemperature components of aeroengine, and the thickness of coating affects its oxidation resistance. In this paper, the signal mutation between the coating and the matrix was used to isolate the time interval between the signal mutation point and the mutation point by wavelet transform. The thickness of the coating was calculated and applied to the thickness of the turbine blade with NiCoCrAlYTa coating Measurement,ultrasonic coating thickness measurement results and metallographic dissection thickness measurement data were compared. The results show that the coating thickness obtained by the ultrasonic coating thickness measurement method is close to that of the metallographic method, and the relative error is about 5% under the average thickness of 150 μm.