The building of an optimized interface between the cocatalyst and the photoactive materials is significant for understanding the charge transfer mechanism and designing high-performance catalysts at atomic level, however, still a great challenge. Herein, we develop a new method to synthesize a class of hybrid photocatalyst by coupling amorphous FeCoPO(x)nanowires (FeCoPOx(NWs)) tog-C3N4 photocataysts (denote as FeCoPOx(NWs)-C3N4) for greatly boosting the photocatalytic activity, which shows 3.5-fold higher H-2-production activity than the state-of-art crystalline FeCoPOy nanoparticles/g-C3N4 hybrid photocataysts (denote as FeCoPOy(NPs)-C3N4). The structure analysis by X-ray absorption fine structure (XAFS) reveals that the Fe species in FeCoPOx(NWs)-C3N4 owns a lower coordination number than that in FeCoPOy(NPs)-C3N4, which can contribute to the formation of strong interface between FeCoPOx(NWs) and g-C3N4. The first-principles simulation confirms that the amorphous FeCoPOx(NWs) not only can build a stable interface with g-C3N4 by forming more Fe-N bonds, but also own an optimized electronic properties for enhancing electron transfer from g-C3N4 to FeCoPOx(NWs). The strong interfacial electronic effect of FeCoPOx(NWs)-C3N4 contributes to its high H-2-production activity.This work not only develops a new method to prepare the high-performance low-cost cocatalyst as Pt alternative for H-2 production, but also provide a new insight into optimizing the interface between cocatalyst and photocatalyst for photocatalytic reaction.