Abstract: In order to explore the automatic measurement of aero-engine blade wall thickness and improve the measurement efficiency and accuracy of aero-engine blades, a 3D cone beam CT (computed tomography) test was performed under different voltages. The 3D CT volume obtained under various voltages was tested. The boundary of the scatter-ray correction and uncorrected scatter-ray at 400 kV and 430 kV was compared, and the extraction boundary of the standard gauge block embedded in the two sets of corrected leaves was also measured. The results show that both CT images tested under 400 kV and 430 kV voltages can extract the blade boundaries clearly, which is relatively close to the actual data.It is demonstrated that the automation measurement of blade can be realized by measuring the blade boundary.