Abstract: Due to the special structure, there is no effective testing method for adhesive interface of non-uniform thickness metal and nonmetallic compound components. The phased array ultrasonic detection technique using auto- focused mode can provide a new idea. This article describes the ultrasonic phased array technique to realize quality detection of interface bonding. The sound field of ultrasonic phased array transducer is established. Based on it, the possibility of using ultrasonic phased array method to detect component with non-uniform thickness is studied. The simulation results show that it is possible to control the radiation beam focused at every desired point by calculating the time delay. This can ensure the amplitude of reflected signal from the interface is almost same. The results indicate that the technique of applying phased array to ultrasonic detection can be used to detect the interface debond of non-uniform thickness metal and nonmetallic compound structure.