Trifluoroacetamidine is a vital chemical intermediate with a wide range of applications. A preparation method comprises the following steps: trifluoroacetamide is used as raw materials, polyphosphoric acid is selected as solvents under the effect of phosphorus pentoxide as dehydrating agents, and trifluoroacetonitrile can be fast prepared through a dehydration reaction. The generated trifluoroacetonitrile gas is introduced into a liquid ammonia kettle after being cooled, and the trifluoroacetamidine can be prepared.
