An assembly structure for subsidiary frame of eyeglasses is provided. A nose pad bracket provided on an eyeglasses major body has an engaging portion having female snap-fit portions provided at both sides thereof to fit with male snap-fit portions on the subsidiary frame. Further, an abutting segment is extended from the surface of a recessed portion on the subsidiary frame in such a manner as to fit with a recessed groove provided on a protruding portion of a nose bridge section of the subsidiary frame. Therefore, one side of the subsidiary frame is pressed against the lenses of the eyeglasses major body and the other side is firmly abutted with the protruding portion, so as to achieve firm positioning of the subsidiary frame and to protect the subsidiary frame from fall off in using.