Abstract: According to the principle of 2D electromagnetic finite element analysis, a transient mathematic model of pulsed eddy current(PEC) testing system considering permeability nonlinear was established and simulation research for oil casing PEC testing process of different drive current was conducted in permeability nonlinear. Through the iterative calculation to permeability by every moment, more accurate results were obtained. Using this model, we achieved the PEC signals detection results corresponding to the different excitation current in 4 mm corrosion depth. According to the test results, we found that due to the material permeability nonlinear, increasing excitation current does not necessarily improve the detection sensitivity.