Abstract: The principle of ultrasonic method and industrial CT used in the measurement of hollow turbine blade wall thickness was compared and analyzed, and the wall thickness at typical sections of DD6 alloy single crystal hollow blade was measured in these two ways respectively, and the test results were compared with the direct measurement of by caliper after cutting the blade. The results show that the accuracy of wall thickness data measured by the industrial CT method is slightly higher than that as measured by ultrasonic testing, but the difference is not obvious. The results by industrial CT method are more convenient for retrospection, while ultrasonic testing method is more efficient.