As an important component of the steam turbine, blades often operate in complex environments with high workloads. Defects such as cracks can pose significant safety hazards to production. In order to detect early-stage cracks, the commonly used material 2Cr12NiMoWV stainless steel in steam turbines was chosen as the research object. A finite element simulation model of an eddy current testing system was established using COMSOL Multiphysics software. This aimed to investigate the impact of different types of defects on the probe coil detection results. The simulation results were validated through experimental equipment.  Furthermore, impedance signals at defect locations were analyzed, providing a theoretical basis and technical support for subsequent defect identification and classification.