Pulsed eddy current testing (PECT) is a non-destructive evaluation technique capable of detecting defects within conductive materials; however, it often encounters challenges in accurately quantifying localized defects. This paper introduces a novel methodological approach and theoretical framework for the identification and quantification of such defects using a high-resolution focusing probe. The effective coverage area of the focusing probe is characterized by a two-dimensional Gaussian distribution model, enabling a detailed analysis of the probe’s interaction with the material under test. Analytical formulas are derived to describe the detection process, providing a foundation for subsequent error analysis. To optimize the detection process, four distinct types of error functions are formulated, and an optimization algorithm is employed to determine the parameters that minimize these error functions. This approach ensures that the probe settings are tailored to the specific characteristics of the defects being investigated. Simulation data are utilized to invert the probe parameters and extract defect information, thereby validating the feasibility and accuracy of the proposed method. The simulation results demonstrate that the method presented in this paper can effectively quantify defects with a high degree of precision. In conclusion, the research presented in this paper offers a significant advancement in the field of PECT by providing a robust method for the accurate quantification of localized defects. This contribution is expected to enhance the reliability and applicability of PECT in various industrial applications where the detection and quantification of defects are critical.