The invention provides a transmission assembly adopting electronic control gear shifting. The transmission assembly comprises a plurality of driving gears with a plurality of predetermined gear shifts and a plurality of synchronizer gear sleeves corresponding to the plurality of driving gears respectively, wherein one side, facing the corresponding driving gear, of each of the synchronizer gear sleeves is the working side; each of the synchronizer gear sleeves is provided with a synchronizer sliding sleeve; an internal spline is arranged on the inner surface of each of the synchronizer sliding sleeves; each of the internal splines comprises internal spline teeth; a coating with a predetermined thickness is arranged on the tooth surfaces, facing the working sides, of the internal spline teeth. According to the transmission assembly adopting electronic control gear shifting, the key stress surfaces of each of the synchronizer gear sleeves are protected by the coating, the problem that greater impact stress and impact noise of parts are caused due to uneasiness in precision control over the motor of an electronic control gear shifting transmission is solved; besides, the hardness of the key stress surfaces of the synchronizer gear sleeves with the coating is improved, the surface roughness is reduced, and a good buffer performance and excellent self-lubricating property are achieved.