Abstract: In order to realize the qualitative analysis of defects in ultrasonic imaging of phased array, partial scattering coefficient matrix is used to characterize the partial scattering field information collected by the sensor, and the defect identification is performed by the partial scattering coefficient matrix chart. Based on the full matrix data acquired by full matrix capture of phased array ultrasound and combined with acoustic attenuation of the propagation process, the partial scattering information of defects is obtained by using the inverse compensation method to compensate the full matrix data to the same circle with the defect as the center, and the partial scattering coefficient matrix is used to represent the partial scattering information. By analyzing the characteristics of the partial scattering coefficient matrix graph of the defect, the defect can be qualitatively analyzed and distinguished. Simulation experiment is carried out by using this method for two typical defects, and results show that obvious differences not only exist in the partial scattering coefficient matrices of both hole and crack defects, but also exist in cracks with different sizes and different angles. It is therefore proven that the method can realize the qualitative identification of defects.