Abstract: During manufacture procedure of IVCs, eccentricity may occur between the inner and outer tubes. Large eccentricity could seriously reduce the insulation property of the middle ceramic layer of IVC conductor and weaken the performance of entire IVC. Therefore, it is necessary to evaluate the eccentricity of IVCs by using non-destructive testing techniques. An eddy current testing method based on flexible probe had been proposed in early studies of authors. To enhance the sensitivity of the eddy current testing method further, in this paper, a numerical simulation was performed based on the reduced magnetic vector potential method (Ar) to investigate the influence of probe size on the testing sensitivity. Simulation results clarified the optimized parameters of flexible probe, and provide a theoretical basis for the design of flexible probe for practical application.