Abstract: CRA pipeline was designed for transferring the gas and oil with high acidic. The diameter of the CRA pipeline is from 168.3 mm to 508 mm with its wall thickness being between 14.1 to 31.6mm with 3mm cladding inside the pipe. Based on the requirement of DNV-OS-F101 (2013), a validation test shall be performed to verify that the height-sizing difference between AUT and macro section of the defect shall be within ±1mm. Due to the difference of the dimension of the CRA pipeline, the AUT technique shall need some adjustment. Based on the pipe with the dimension O.D 508 mm, W.T 31.6mm (internal cladding 3 mm), the article describes the details of project validation method, which includes AUT calibration, defective welds manufacturing, scanning, macro sectioning and data analysis, so as to evaluate the detection ability and height sizing accuracy of the AUT technique. It is hopeful that the practical application of the above-mentioned method in the inspection of the girth welds of CRA subsea pipeline shall be realized.