Abstract: Magnetic flux leakage is one type of electromagnetic nondestructive testing (NDT) which is widely utilized in the testing the integrity of drill pipe in the field. In this paper, the 3D model of excitation unit is completely built and analyzed by ANSYS software. The magnetic field of drill pipe in the combination of full excitation device is shown by ANSYS software instead of the physic experiments which increases the efficiency tremendously and decreases the cost and achieves the anticipated desire. It is considered that this technique can provide the theoretical basis of drill pipe excitation device and the magnetic flux leakage testing of drill pipe.