Abstract: The basic gold purity inspection method is introduced simply and the new gold inspection technology by ultrasonic phased array is focused in this paper. The principle of using phased array technology to inspect gold bar is analyzed. The ultrasonic phased array technology is reliable in gold inspection application which is verified by experiment. The result is that ultrasonic phased array technology could find the gas pore, inclusion defect and distinguish the 24K from 18K gold.