Novel yard-glass shaped boron nitride nanotubes (YG-BNNTs) periodically filled with Fe nanoparticles were synthesized by a catalytic reaction process of ammonia with boron precursors at 1300 degrees C. Such novel structures were extensively characterized using X-ray diffraction and advanced electron microscopy. The Fe-filled boron nitride nanotubes show excellent ferromagnetic properties at room temperature with superior chemical stability. A growth model is proposed for the formation of such novel BN nanostructures.