Abstract: The visual inspection technique based on the automated vision has many advantages, such as noncontact, high speed, accurate and online etc. It is widely used in the online examination of the industrial product. CCD camera is the key part in the Automated Visual Inspection. The accuracy of the examination is based on the CCD′s parameter. So the calibration of CCD is critical for the process. In order to resolve the problems caused by traditional calibration methods, a new method is introduced to calibrate the tubing thread measurement system. The new griddedparallel line calibration method adopts CCD subpixel technique. Theoretical analysis and experimental results show this method has the advantages of high accuracy, easy operation and good repeatability.