The invention disclosed a method of manufacturing the thin film, which belongs to the technological field of SOI wafer manufacture. By growing a layer of dielectric material (silicon oxide) on the provided high-resistivity silicon wafer, then to grow a layer of amorphous silicon on the dielectric material, to transfer a layer of silicon oxide to the amorphous silicon, to make the mono crystalline silicon exist on the oxidation layer, so that a SOI wafer with a layer of amorphous silicon is manufactured. The process above is completed in specific process conditions. The manufactured thin film, e.g. SOI wafer with amorphous silicon layer, is used main for RF apparatus.