In order to get the good performance of metal W reinforced Zr-based bulk metallicglass (BMG) matrix composites, it is necessary to understand the effects of alloy elements on the wettability between Zr-based BMG and W substrate. In this work, the effects of the addition of Ti or Al on the wetting behaviors and interfacial characteristics of Zr₅₀Cu₅₀ BMG on W substrate were studied at different temperatures in a high vacuum by using a sessile drop technique. The SEM and XRD were used to analyze the microstructure and bonding mechanism of the Zr₅₀Cu₅₀ BMG / W interface with the addition of Ti or Al element. The results show that the wetting angle of Zr₅₀Cu₅₀ molten alloy on W substrate decreases with increasing content of Ti or Al in liquid Zr₅₀Cu₅₀ and experimental temperature. The wettability of Zr₅₀Cu₅₀ BMG on W substrates is improved because the surface tension of Zr₅₀Cu₅₀ molten alloy decreases with increasing content of Ti or Al. It is found that the behavior between Zr₅₀Cu₅₀ BMG and W substrate is reactive wetting in nature, and there exists a new ZrW₂ phase precipitated in the vicinity of the Zr₅₀Cu₅₀ BMG /W interface. The addition of Ti or Al element has different effects on the microstructure and bonding mechanism of Zr₅₀Cu₅₀ BMG /W interface. On the one hand, the addition of Al element promotes the interfacial reaction. With increasing content of Al, continuous reaction layers of ZrW₂ phase in the interface reduce, and there are massive precipitates of Al--rich and Cu--poor phases in molten Zr₅₀Cu₅₀ alloy. On the other hand, the addition of Ti element restrains the interfacial reaction which gradually disappears with increasing content of Ti.