The utility model relates to the technology of speed changing boxes, in particular to a speed changing box of a motor-driven gearshift. The speed changing box comprises a gear shifting mechanism and an executing mechanism. The gear shifting mechanism comprises a first gear shifting motor, a first roller screw, a first gear shifting fork, a second gear shifting motor, a second roller screw and a second gear shifting fork, wherein the first roller screw is connected with the output shaft of the first gear shifting motor, an inner threaded sleeve is arranged at the upper end of the first gear shifting fork and is in threaded connection with the first roller screw, the second roller screw is connected with the output shaft of the second gear shifting motor, and an inner threaded sleeve is arranged at the upper end of the second gear shifting fork and is in threaded connection with the second roller screw. The motors are used for replacing air cylinders or oil cylinders, so that gear shifting force is stably output, and gear shifting is more accurate; furthermore, due to the fact that stress on the gear shifting forks is large, the design of fork shafts and guide blocks is adopted, so that the gear shifting forks are not directly connected with the roller screws, and thus the roller screws are protected against damage.