A nano-patterned system comprises a vacuum chamber, a sample stage and a magnetic-field applying device, which comprises a power supply, a magnetic-field generation device and a pair of magnetic poles. The magnetic-field generation device comprises a coil and a magnetic conductive soft iron core. The power supply is connected to the coil, which is wound on the soft iron core to generate a magnetic field. The soft iron core is of a semi-closed frame structure and the magnetic poles are at the ends of the frame structure. The stage is inside a vacuum chamber. The poles are oppositely arranged inside the vacuum chamber relative to the stage. The coil and the soft iron core are outside the vacuum chamber. The soft iron core leads the magnetic field generated by the coil into the vacuum chamber. The magnetic poles locate a sample on the stage and apply a local magnetic field.