Defect size of wall thinned pipe is measured by using Speckle Shearing Interferometry (SSI) and Digital Image Correlation (DIC) techniques. A wall thinned defect of a carbon steel pipe was typically caused by flow accelerated corrosion (FAC). As wall thinned pipe can cause a huge accident at the nuclear power plant (NPP), a wall thinned defect should be detected for structure safety. SSI is one of the optical nondestructive techniques and can provide to inspect in real-time and to measure on the whole visible area at a time. DIC is a kind of the visual testing method. This method which uses a stereo vision system can measure the deformation or strain/stress of a structure in 3D. In this paper, ASTM A106 Gr.B carbon steel pipe is used as specimen. When the pressure load is provided by the pressure pump, the out-of-plane deformation along the longitudinal direction of a pipe can be detected quantitatively. Both results of SSI and DIC experiments are compared.