Abstract: Industrial computed tomography is widely used in ray non-destructive testing technology.The measurement of 3D image is an important component of industrial computed tomography.In the paper,ridgelet transform is used in 3D image measurement of industrial computed tomography.Radon transform is used on 3D image at first.Then two-dimensional image(called projection image) is gotten by the projections.A straight line was drawn in the measured position.Wavelet transform is used in the pixels which are on the straight line.Then the two edge positions on the line can be judged by the wavelet coefficients and the distance between two points is obtained.The simulation results show that the accuracy of using the ridgelet method to measure the distance between two points in space is high.