It is well recognized that amorphous alloys usually offer much higher resistance to corrosion over their conventional counterparts in most aqueous solutions. Whereas, in this work, we reported an anomalous corrosion resistance of an arc melting Zr_62.3Cu_22.5Fe_4.9Al_6.8Ag_3.5 crystalline alloy, which was superior to that of the same composition in glassy state in simulated seawater. It was revealed that the easy formation of a highly protective Zr- and Al-enriched oxide layer at the surface of the crystalline alloy is responsible for the extremely high corrosion resistance. The current finding not only presents an excellent alloy candidate for potential application in seawater but provides a new insight into the understanding of corrosion behavior of amorphous/crystalline alloys in demanding corrosive media.