Abstract: The optimal distribution of the gas as the by-product of an iron and steel complex between the gas holder and the boiler in its self-supply power plant is discussed, involving the effects of the position control of gas holders, change in fuel loading of the boiler and variation of purchase price of additional fuel on the cost of operation. An optimal gas distribution model is thus developed with a relevant penalty function deduced to solve these problems. The results indicated that the optimal gas distribution between gas holders and self-supply power plant is available to decrease the fuel purchased externally and reduce the frequent change in fuel loading of the boiler, thus improving the power supply efficiency and enabling the zero gas emission so as to make the operation of gas supply system safe, economic and stable.