The invention relates to a transverse cutting machine for cutting ultrathin plate glass, which comprises a bracket (1), wherein the bracket is matched and connected with a set of support rollers (4); both sides of the bracket are respectively provided with a column (3); the upper end of each column is connected with an upper cross beam (2); the upper cross beam (2) is arranged above the support rollers; a horizontal movement device (11) is arranged in the upper cross beam and connected with a hoisting gear (6); and the hoisting gear is connected with a cutting knife (7). The transverse cutting machine is characterized in that the lower part of the column is also connected with a lower cross beam (8), and a horizontal movement device is also arranged in the lower cross beam which is also connected with a hoisting gear; the hoisting gear is connected with a roller (9); and the roller is synchronously and correspondingly matched with the cutting knife. The transverse cutting machine is simple in structure and convenient to assemble; and when the transverse cutting machine is used for cutting ultrathin plate glass, the cutting knife is always pressed on the roller and can not rupture the glass, so the use effect is good.