The cluster rules of alloy phase structure of some typical bulk metallic glass systems were studied. The fact that the clusters share atoms each other in different ways in the alloy phase was pointed out. After sharing there are two kinds of cluster linkages: the first is the phase composition which does not need glue atoms; the other is that glue atoms are required to form phase structure, i.e. termed cluster phases. The method provides a new idea for the structure of alloy phase. In the typical bulk metallic glass system Zr-Al-Ni, there are three cluster phases, AlNiZr-Fe2P, Al2NiZr6-InMg2 and Al5Ni3Zr2-Mn23Th6. The method to determine the clusters related with metallic glass formation based on alloy phase structure was also put forward, i.e. the clusters related with the metallic glasses are generally the isolated clusters from cluster phases, which is verified very well in Zr-Al-Ni system.