The utility model belongs to the field of pharmaceutical machinery, and in particular relates to a device for preparing a key intermediate of trospium chloride. The device comprises a bracket (1), wherein a reaction kettle (3) is arranged on the bracket; a stirring device and a lifting device are arranged on the upper part of the reaction kettle (3); a base plate (14) and a three-way discharge valve (15) are arranged at the bottom of the reaction kettle (3); a transfer pump (16) and a bag-type filter (17) are connected to the lower part of the three-way discharge valve; the transfer pump (16), the bag-type filter (17) and the three-way discharge valve are connected with a tank body (7) through a pipeline; the tank body (7) is connected to the reaction kettle (3). The device is easy to operate, high in yield and low in cost; a synthesis process is implemented in the closed tank body, so that the quality of a trospium chloride intermediate product is improved, high product stability is ensured, and the labor intensity is greatly lowered.