To develop biosensors with the capability of detecting very small mount of biological agents, such as single or several cells, magnetostrictive bars or stripes in size from nanometer to micrometer are required. In this paper, magnetostrictive nanobars and nanobar arrays, with a diameter from 50 to 200 nm and a length of 2-5 μm, were fabricated based on template-based synthesis. The amorphous Fe-B alloy was selected as the magnetostrictive material to fabricate the nanobars. The study on resonance behavior and magnetic properties of plated Fe-B thin films indicate that amorphous Fe-B alloy is a good candidate for fabricating high performance sensor platform. The magnetization hysteresis loop of Fe-B nanobars was characterized. It is found that all the nanobar arrays exhibit easy axis of magnetization along bar length direction but with smaller coercivity, which is different with bulk materials. The physics behind the phenomena is discussed.