Ultrasonic Infrared Imaging is a novel NDE technique,which performs well for material internal defect detection such as metal fatigue crack,composite material impact damage and adhesion etc.Traditional defect identification depends on eyes and professional experience,which can′t give a clear conclusion of defect information.The identification algorithm based on time sequence images is low-level.Therefore,taking the crack detecting of Ultrasonic IR for example,after contrastive analysis of shape characters and gray distribution between crack region and normal region,characteristic parameters for different regions are creatively extracted in this paper.An automatic recognition algorithm based on Weighted Support Vector Machines (Weighted SVM) is put forward for crack region recognition.Subsequently,the correctness of the algorithm is validated by experiments.