Abstract: In order to solve the problem of low accuracy of strip width real-time detection technology, a bilateral tracking strip width gauge based on area array CCD (charge coupled device) was designed. In order to reduce the edge imaging error, the area array CCD camera was used to collect the edge image of strip. In view of the large up-down jitter of strip during high-speed movement, a bilateral tracking method was adopted to make the camera follow the edge of strip and reduce the field of view error of area array CCD camera. Differential edge detection algorithm based on ROI (region of interest) of large and small field of view was used to detect strip edge, which could reduce the error caused by iron chip dropping and strip edge mutation. Field test results show that the designed strip width gauge can detect strips with uneven edges and big up-down jitter, and can avoid the errors caused by iron chip dropping and edge mutation effectively. The accuracy of ROI differential edge detection algorithm with large and small dual field of view can reach 0.055 mm, the frame rate of the algorithm can reach 46 F/s, the overall width accuracy can be controlled within 1 mm, and the measurement frame rate can reach 20 F/s, which meets the requirements of high precision and real-time detection.