The dry-sliding tribological properties of the dendrite composite eutectic Fe-B alloys (Fe94.3 B5.7 , Fe75 B25 Fe67 B33 ) were studied comparatively with various sliding speeds. The friction coefficient of the Fe-B alloy changes slightly with the boron content. The wear rate of the Fe94.3 B5.7 alloy with about 30 vol. % dendrite t-Fe2 B is only one third of Fe75 B25 alloy with 15 vol. % dendrite and Fe67 B33 alloy with 90 vol. % dendrite in the high sliding speed. First, a hard t-Fe2 B phase reduced the wear of the Fe-B alloy directly. Second, the compactly oxide layers resulting from oxidation of the α-Fe on the worn surfaces also decreases the wear rate of Fe-B alloys. On the whole, the wear rate of the Fe94.3 B5.7 is lower than Fe67 B33 and Fe75 B25 .