Aiming at the problem that eddy current signal was easily disturbed by the excitation magnetic field and background magnetic noise, the method of PECT based on ferromagnetic shielding was proposed. The finite element simulation model with ferromagnetic shielding was established on the base of the theoretical analysis of magnetic shielding. The simulation result showed that the component of eddy current became intensive under the ferromagnetic shielding, although it weakened the amplitude of the testing signal. The defects of different depth can be easily recognized and the sensitivity of signal is effectively improved. According to the results of finite element simulation,the magnetic shield of ferromagnetic materialis manufactured. The experimental result indicates that magnetic shielding can effectively enhance the sensitivity of testing on the surface defects of ferromagnetic metal, whereas the method cannot improve the detection effect on the subsurface defects of ferromagnetic metal.