The erosion-corrosion behavior of directional solidification Fe-3.5B alloy in flowing liquid zinc was investigated by rotating disk technique. Microstructural morphology of erosion-corrosion interface was observed by SEM, the effects of orientation and space of Fe2B on the erosion-corrosion in the flowing liquid zinc were analyzed. The results show that the erosion rate quickly decreases with the extension of erosion time when the Fe2B is parallel to the flowing direction of liquid zinc (labeled Fe2B∥ sample) and the erosion rate slowly decreases with the extension of corrosion time when the Fe2B is perpendicular to the flowing direction of liquid zinc (labeled Fe2B⊥ sample). The erosion rate of directional solidification Fe-3.5B alloy (Fe2B∥ sample) increases first and then decreases with the increase of Fe2B space. When the space of Fe2B is 3.67μm, the corrosion rate of transverse sample possesses the minimum value of erosion-corrosion rate. The corrosion rate of longitudinal sample reaches the minimum value of erosion-corrosion rate when the space of Fe2B is 1.87μm. The microstructure of erosion-corrosion interface is dependent on the Fe2B space, and the appropriate Fe2B space is beneficial to form a good erosion compound layer which shows an “interface pinning effect” and inhibits erosion-corrosion.