Hydration treatments were performed on the pure aluminum substrate at $100^{circ}C$ followed by anodizing and heat treatments on the layers. The transformation behaviors of the oxide layers according to the hydration treatment were studied using TEM, XRD, RBS etc. Above $90^{circ}C$ the hydrous oxide film could be formed, which were turned out to be hydrous oxides(AlOOH $nH_2$O). The anodization on the hydrous oxide film was more effective for the transition of amorphous anodic oxides to the crystalline $Upsilon-Al_2$ $O_3$ comparing with the case for anodizing on the aluminum substrate without hydration treatment And additional heat treatments were also helpful for the acceleration of the transformation of the hydrous oxide to $Upsilon-Al_2$ $O_3$. During the heat treatment the interface between $Upsilon-Al_2$ $O_3$and the hydrous oxide layers migrated to the outer side of hydrous layer.