The invention belongs to a method for preparing barium sulfate particles through a microchannel method in the technical field of nanomaterial preparation. The method comprises the following steps: introducing a sulfate water solution and a barium salt water solution into a microchannel reactor for reacting and ageing, and centrifuging, washing and drying an obtained reaction solution, thus obtaining the barium sulfate particles, wherein selected sulfate is sodium sulfate, ammonium sulfate or sodium persulfate, and barium salt is barium chloride, barium acetate or barium nitrate. The morphologyand the particle size distribution of the obtained barium sulfate particles are controllable, and industrial application of medical dry films can be met to a larger extent.