Addition of rare earth elements can significantly improve the glass forming ability of Fe-based alloys. But the magnetic domain that most of the rare earths possess themselves always worsens soft magnetic properties of the alloys. By contrast, the rare earth element Y does not have this kind of magnetic domain itself, and is an ideal candidate to add to the Fe-based amorphous alloys as soft magnetic materials. In order to systematically study the effect of partial substitution of Fe in Fe78Si9B13 alloy with rare earth element Y on glass forming ability and soft magnetic properties, a series of wedge-shaped specimens and amorphous ribbons are prepared by copper mold suction casting and melt spinning respectively. It is found that the replacement of Fe by minor Y enhances the glass forming ability of the alloy. When 3 at.% Fe is replaced, the critical thickness and supercooled liquid region of the amorphous alloy reach their maximum values, 313 μm and 65 K, respectively. The amorphous alloys have excellent soft magnetic properties: coercive force (Hc) all bellow 200 A/m and saturation magnetic induction (Bs) all above 1.30 T. Specially, Bs reaches a maximal value, 1.67 T, when 1 at.% Fe is substituted.