Reduced density function analyses for the bulk amorphous alloyZr41Ti14Cu12.5Ni10Be22.5and its decomposition and crystallization have been made by means of electron diffraction intensity measurement with imaging plate. The local atomic structure of the amorphous alloy as well as its development in the course of the decomposition and crystallization is described from the analysis of the atomic distribution function. The origin of the high thermal stability and the large glass forming ability of the alloy as well as the effect of the decomposition on the crystallization is discussed from the viewpoint of the local atomic structure characteristics of the alloy. ©1997 American Institute of Physics.