Abstract: Radiation beam field characteristics of a 2D ultrasonic matrix phased array transducer mounted on angle wedge are studied under the condition of an interface.The issue about a matrix phased array transducer with an angle wedge is reasonably simplified into a liquid-solid interface problem.Based on the acoustic field theory produced by a single element on the liquid-solid interface,the focus laws are derived and the approach that can calculate the 2D ultrasonic matrix array radiation beam field with a liquid-solid interface is obtained.In order to investigate the characteristics of radiation beam patterns in steel specimen,simulation is carried out for 5 MHz,8×8 elements array transducers mounted on an acrylic wedge with the angle of 36° with various of steering angle and focal planes.It is shown that the calculation model can efficiently predict the radiation beam field of a 2D ultrasonic matrix array with the wedge,and the proposed approach is expected to provide guidance for matrix array angle beam probe design.