The invention discloses a reaction device for preparing glucosamine through biotransformation fermentation. The reaction device comprises a controller, a kettle body, a kettle lid, a stirring motor and a stirring shaft; the stirring shaft is fixedly provided with a mounting plate, a first fixed block and a second fixed block are fixed under the mounting plate, the first fixed block is connected with a first cylinder, the free end of the first cylinder is connected with a first movable rod, the second fixed block is connected with a second cylinder, the free end of the second cylinder is connected with a second movable rod, the stirring shaft is connected with a first cross bar and a second cross bar, a first sleeve rod sleeves the first cross bar, a first scraper plate is hinged to the end portion of the first sleeve rod, a first stretching spring is connected between the first sleeve rod and the stirring shaft, a second sleeve rod sleeves the second cross bar, a second scraper plate is hinged to the end portion of the second sleeve rod, and a second stretching spring is connected between the second sleeve rod and the stirring shaft. The reaction device can prevent a material from adhering and settling.