Based on pair distribution function studies, a structural parameter, derived from the number of cluster connecting bonds and the coordination number, and energy analysis have been introduced to describe different kinds of local clusters in the liquids and glasses. By applying these analyses to a widely studied Zr–Cu–Al base alloy system, we found that Zr-, Cu- and Al-centered first shell clusters showed different structural evolution and energy distributions during cooling. In terms of their structure and energy states, it is confirmed that the Al-centered first shell clusters play dominant role in the appearance of glass transition prior to the crystallization.