The invention discloses a maintenance-free connecting device and method for a large wind driven generator tower. The maintenance-free connecting device comprises a connecting part which is used for bearing transverse loads which are caused to the draught fan tower under the common effect of the capsizing moment of wind and various kinds of vibration in draught fan operation. The connecting part is arranged in a bolt connecting combination of the draught fan tower. The maintenance-free connecting device and method have the beneficial effects that operation is simple and convenient, a gap between a connecting bolt and a hole wall of the bolt can be completely eliminated, and a certain magnitude of interference is formed; meanwhile, huge pressing force is generated between the connecting bolt and the hole wall of the bolt, reliable connection is achieved, and therefore transverse loads can be borne; and meanwhile the installing and manufacturing cost is obviously reduced, the device is applied to the part between tower flanges to form connection, no relative displacement exists between the tower flanges, and in other words, the two butt joint flanges are riveted into a whole. Thus, connection loosening cannot be caused to the tower when the tower is subjected to static loads, dynamic loads, the capsizing moment of the wind and various kinds of vibration, the bolt loosening problem is solved fundamentally, and the connecting bolt does not need to be checked or maintained within the continuous service life of 20 years of a draught fan.