Abstract: For the curvature workpieces in the casting forging and welding fields, the traditional phased array probe cannot get good coupling and it requires preparing various contour wedges to ensure the coupling quality, thus it is time consuming and high cost. These problems seem to be solved by using the flexible phased array technique, but how to determine the focal law of the flexible phased array transducer is also a hard task. In this paper, based on the phased array acoustic principle, the time delay focal law of flexible phased array transducer is addressed. Then the sound field propagation model is established using the finite element method to verify the accuracy of this provided delay focus law. Finally, the detection simulation of curved workpiece with embedded defect is carried out. The experiment results illustrate that the flexible phased array technology can obtain high efficiency and high precision nondestructive testing of tiny defects in the curved workpiece