MFLThe current magnetic flux leakage (MFL) inspection technique can detect and locate defects on both the internal and external walls of drill pipe, but is generally unable to differentiate between internal and external defects. This paper presents a new method to distinguish between internal and external defects based on weak magnetic inspection. The study is undertaken using extensive finite element analysis (FEA), focusing on the 3D magnetic field distribution of internal and external defects in both strong and weak magnetic regions. Through the 3D magnetic flux density vector diagram and the axial and radial component diagram of the magnetic leakage field of the defects, the characteristics of the magnetic leakage field around defects are obtained intuitively, which demonstrates that weak magnetic inspection can be used as a method for internal and external defect recognition. The experimental test results show that such discrimination is viable using weak magnetic inspection.Keywords: 3D FEM, magnetic flux leakage testing, weak magnetic inspection, internal and external defect identification.