Abstract: The technology of depositing different material foils on Mylar films by vacuum evaporation was systematically studied. The radiation heat from evaporation source and condensation heat of depositing, which raise the temperature of the substrate in the process of depositing foils by vacuum evaporation, were discussed in detail. An accurate method of controlling thickness was introduced. The homogeneity of depositing foils was calculated and measured for static substrate and rotating substrate, respectively. Methods of preventing Mylar films from softening were explored and summarized. Two dozen kinds of material foils, e.g. Sc, Ti etc., with thickness of 1 μg/cm² and 20 μg/cm² respectively deposited on 12.5 μm Mylar films were successfully prepared, which are required by physics experiments. Finally, the uniformity of Cu and Cr foils deposited on Mylar films was measured by X-fluorometric analysis. Results show that the uniformity is better than 5%, which fully satisfies the requirement of physical experiment.