<正> In observance of the position of foam line varying with different refractories in glass tank, furnace, it is believed that this phenomenon is caused by the different thermal conductivities of refractories. Choosing suitable feeders and correct ways of charging are considered very important in well-controlling the foam line. The adoption of a combination of 2 feeders for charging side by side is preferable. Moreover, a rational longitudinal temperature distribution in glass tank furnace, also plays a key role in controlling foam line.