Controlling the fluctuation of bare fiber diameter in the process of optical fiber drawing is an important factor affecting the quality of optical fiber drawing. The data model of the optical fiber drawing process is given, the factors affecting the bare fiber fluctuation in the optical fiber drawing are analyzed, the whole process of optical fiber drawing is introduced, the sampling data of the bare fiber diameter fluctuation by the temperature field and gas flow field in the furnace are tested, and the corresponding experiments are designed according to the furnace structure, gas matching and flow rate. The experimental data show that by changing the structure of heating furnace and drawing tower and the flow rate and configuration of inert gas, the disturbance of drawing manufacturing process can be reduced and the control accuracy of bare fiber diameter fluctuation can be improved. The fluctuation range of fiber diameter is from ±1 μm increased to ±0.5 μm