The invention is applicable to the technical field of fluoridation synthesis, and provides a microchannel reactor for a fluoridation reaction and a preparing method thereof. The microchannel reactor comprises a body with a reaction channel, the bottom of the body is provided with a feeding pipe which is communicated with an inlet of the reaction channel, and the top of the body is provided with adischarging pipe which is communicated with an outlet of the reaction channel. The feeding pipe is communicated with a reaction chamber, and the reaction chamber is communicated with a first inlet anda second inlet separately. The body is prepared from a ceramic material through a 3D printing technology. According to the microchannel reactor and the preparing method thereof, the microchannel reactor with a refined structure can be quickly prepared through the 3D printing technology, the preparing method is particularly used for preparation of three-dimensional ceramic microchannel reactors with complicated structures, and preparation of the microchannel reactor is convenient and quick. The microchannel reactor is made from the ceramic material, and has a very large specific surface area and heat exchange performance, the fluoridation reaction can be safely and efficiently carried out with high speed and high efficiency, continuous production is achieved, industrial enlargement is easyto achieve, and industrialization is achieved.