The invention discloses a rearview mirror control device for eliminating turning blind areas and a control method thereof. In the turning process, the view fields of external rearview mirrors are regulated by automatically regulating the angles of the external rearview mirrors, so that side blind areas can be eliminated very effectively. The rearview mirror control device comprises external electric rearview mirrors, electric rearview mirror driving circuits, a controller, a left-turning electric rearview mirror switch, a right-turning electric rearview mirror switch and a turn light sensor, wherein the controller is connected with the left-turning electric rearview mirror switch, the right-turning electric rearview mirror switch, the turn light sensor and the electric rearview mirror driving circuits respectively; the external electric rearview mirrors are connected with the electric rearview mirror driving circuits; and the turn light sensor detects the state of a turn light switch. The control method is as follows: when a vehicle turns right, a turn light control rod rotates clockwise to a limit position, an external left rearview mirror rotates outwards for a set angle, and the view field of the external left rearview mirror is broadened; after the vehicle turns right, the external left rearview mirror returns to a normal angle; and the like.