Abstract: The sound fields of the focusing and steering beam radiating from the phased arrays are nonuniform according to different spatial positions,so that the echo signals of same size defects will be changed with positions.To analyze defects quantitatively,a model-based distance amplitude correction is proposed for the phased array system.Based on non-paraxial multi-Gaussian beam model and flaw scattering model,ultrasonic measurement model for the phased array system is proposed to calculate the echo signals from side-drilled holes at different positions.Furthermore,the modelbased distance amplitude curves are compared with traditional experimental results in the case of different focusing and steering beam.It is shown that two methods have a good agreement.The deviation are within 5%.