The amorphous Ni88P12 alloy films were prepared on the p-Si(100) substrate by chemical deposition in solution at 363K. The structure, composition and morphology of the films were studied by STM, AFM, XRD and XPS before and after the treatment of oxidation, reduction and crystallization. The results showed that the amorphous Ni88P12 alloy film was in the form of the micrometre-scale grains and each of which consisted of nanoparticles. The surface crystallization started as the films were oxidized and reduced at the temperature lower than that at which crystallization occurred. The morphological feature of the crystallites developed from the nanophase of the amorphous film was also observed after crystallization.