Abstract: In order to study the processing quality of the laser hardened workpiece, a dynamic detecting system of laser hardening was developed in which a CCD camera was used to capture the thermal radiation images in laser hardening process. The oversaturated phenomenon can be eliminated during the detecting process by selecting the CCD model reasonably. The images of the object were taken by the CCD camera. Then the image data were analyzed by a computer so that image processing made the gray value distribution display clearly, and the hardened band width was obtained by pseudo-color and threshold segmentation processing, which made the software system was developed successfully. The experimental results show that this system can accurately measure the hardened band width, which will contribute to a closed-loop control system for laser hardening for improvement in hardening quality.