Abstract: The microstructures of An films deposital on polyvinyl formal （PVF） substrathe at various temperature have been investigated using TEM （Transmission Electron Microscope）.Transition from compact islands to fractal structures has been observed when substratetemperature decreased. The films of An deposital on PVF at 213~253K show flactal characteristic. The fractal dimension was measured using the Sandbox method. The fractal dimensions increase with increasing film thickness and raising substrate temperature. An empty areas, about a circle, was formed around the fractal sstucture of Au films. This phenomenon show that islands or clusters can be mobile. They aggregated to large islands or ramified stures. The experimental results have been discussed by using the models of DLA （Diffusion-Aggregation） with active adge diffusion and CCA （Cluster-Cluster-Aggregation）.