The invention relates to the technical field of float-process glass production, and in particular relates to a float-process glass production apparatus and method related to a melting furnace with two production lines. The method is characterized by employing the production lines branched vertically and transversely and comprising the following steps of: (1) feeding the melted and clarified glass liquid into the cooling part of a melting furnace, and then entering into horizontal production lines at the left and right sides through stream guidance at a triangular region under the action of vitreous humour convectio; (2) entering the glass liquid at the left side into a first tin bath through a first flow channel and forming, while entering the glass liquid at the right side into a second tin bath through a second flow channel and forming; and (3) conveying the formed glass plate at the left side to a first annealing furnace and a first cold-end cutting device through a first transition roller table, thereby obtaining a finished product; and conveying the formed glass plate at the right side to a second annealing furnace and a second cold-end cutting device through a second transition roller table, thereby obtaining a finished product. Compared with the existing longitudinally parallel branched production lines, the production lines branched vertically and transversely are smoother for the liquid to flow and guarantee the uniformity of the glass liquid and appropriate cooling strength.