Abstract: To prevent important items from being forged and replaced, this paper presents a concept of ultrasonic fingerprint. Ultrasonic phased array is used to detect the unique echo of each item to get the ultrasonic fingerprint. The target item can be accurately recognized by ultrasonic fingerprint even if it is mixed with others which have the same appearance and material composition. The result shows that a variety of metallic samples can be identified effectively using ultrasonic phased array recognition system. This system provides a new approach for the protection and recognition of valued items.