Abstract: According to the problems that longitudinal and transverse defects of steel pipe are tested separately by magnetic flux leakage inspection, four methods of magnetization for steel pipe based on coaxial single-coil, oblique single-coil, oblique single-coil with a magnetic component for collecting magnetic field and coaxial single-coil with it were proposed and analysed. It concluded that an oblique single-coil was the necessary conditions for producing oblique magnetic field and the magnetic component could increase it. The conclusion was validated by experiments. Finally, a method of magnetic flux leakage inspection for longitudinal and transverse defects of steel pipe simultaneous detecting based on oblique magnetization by single coil was put forward.