Abstract: Ultrasonic IR Thermal is a novel NDE technique, which combines a short ultrasonic pulse excitation and infrared imaging to detect defects, such as crack, in materials and structures. A simplified one-dimension heat-conduction model excited by ultrasonic pulses was put forward in this paper. Based on this model, a series of image processing methods for identification and reconstruction of cracks were presented. Results obtained showed the methods were feasible and accurate.