Blast furnace operation, the most important process in iron making, is improving in the world, continuously.The big problem in blast furnace operation is availability of coke due to the high cost of this product. Therefore, finding the ways to reduce coke consumption rate with specific production of iron is needed. In present study, blast furnace operation is modeled by conservation equations of mass, energy and availability which is useful for iron and steel industry.According to this modeling, blast furnace is considered as a control volume with specific inputs and outputs. Inputs and outputs of this control volume are selected by according to real operation of blast furnace. In this project, blast furnace conditions are considered stable and steady state. Based on used equations in modeling, a simple computer program is created. A comparison between actual operation of real blast furnace and model predictions is created.The coke consumption rate and blast rate, based on model results are calculated 3.16% and 8.3% lower than real values, respectively. The first thermodynamic law of blast furnace is calculated 86.1% based on model predictions. From energy conservation useful results is achieved in relation with energy input and consumption, but there is not any information about maximum useful reversible work of blast furnace. Therefore, availability conservation should be established. According to results of availability conservation, the second thermodynamic law of blast furnace is calculated 48.92%. Moreover, irreversibility of blast furnace is estimated 51.08%. The high value of this irreversibility is due to ignition process in blast furnace. A comparison between availabilities of model results and the real data is established, which shows good agreements with real conditions. The results derived from model illustrate that, by use of coke with lower ash, rate of coke consumption and blast volume are decreased. Also, decrease of the reduced Silicon and reduce of Carbon and Manganese in molten iron, effect reduction influence on coke and blast rate. Another parameter which is important in coke and blast rate is temperature and pressure of blast. By increase of the temperature and pressure of blast, the rate of coke consumption is reduced. The rate of blast behaves the same. Moreover, if the volume of natural gas decreases, coke consumption rate is reduced, but it does not have significant effect on blast rate. Slag volume, has the inverse effect on coke and blast rate, decrease of slag volume will reduce the coke consumption rate and blast rate. Also, by compressing blast, the rate of blast will be reduced. These operations conclude improvement of thermal efficiency. Key Words: Blast Furnace, Modeling, Thermal Efficiency, Availability, Fuel Consumption