1-Naphthaleneboronic acid (0.41 mol), potassium difluoride (0.82 mol), stirred at a high speed of 500 rpm for 10 minutes to obtain a uniformly mixed material, which was continuously added through the feed port of the twin-screw extruder, and the extrusion time Set to 5 minutes, the extruded material is directly received in the receiver containing the same weight of water as the solid material, stirred and dispersed to obtain a slurry, filtered, the filtrate is returned to the receiver, and the filter cake is washed with water and dried with hot air to obtain the product Potassium (1-naphthalene)trifluoroborate.