Metastable structure and structural changes of Cu-Ag, Cu-Al, Ag-Al, Cu-Ag-Al alloy films prepared by co-evaporation, onto cooled substrates have been, investigated systematically, and some unique phenomena are exhibited in the amorphous formation and crystallization. It is generally observed that the as-deposited amorphous films tend to present homogeneous solid solution with fcc lattice at the first step of crystallization, and undergo a step-by-step structural change proceeding before reaching the final equilibrium states. The laser induced crystallization of amorphous Cu29, Al71 film also shows such a unique behaviour, and it makes us propose that the above alloys may be the promising candidates as phase change optical storage materials.