The invention relates to a one-kiln three-line float glass production line and solves problems of a large unit consumption of a fusion fuel, poor quality of liquid glass and high cost in enterprise production since a fusion capability of a glass fusion kiln in the prior art is beyond a pull capacity of the float glass production line, which causes that a saturate situation of the glass fusion kiln cannot be achieved. A flow dividing apparatus is arranged behind a first-stage clamp neck and is provided with three flow paths which divide the liquid glass from the first-stage clamp neck. A sum of the pull capacity of the three flow paths is matched with the fusion capacity of the glass fusion kiln. Each flow path is successively connected to a secondary clamp neck and a cooling part. The cooling part is connected to a float glass producing tin tank and a subsequent apparatus. A production line corresponding to one flow path of the three flow paths is co-axial with the first-stage clamp neck. The liquid glass in the fusion kiln is distributed according to the pull capacity of each of the three flow paths so that a large-tonnage glass fusion kiln is in a saturated work situation. The one-kiln three-line float glass production line can reduce the unit consumption of the fuel, can improve production efficiency of float glass production and can reduce the cost in enterprise production.