The effect of the combustion chamber's configuration on the characteristics of flow and combustion parameters has been numerically investigated for a multi injecting, LPG, Flameless Oxy-fuel burner in a real-size soaking pit furnace, using CFD simulation. The simulation has been performed on two different furnace configurations, namely; small and large chambers of 15 m 3 and 27 m 3 , with a height to width ratios of 1.49 and 2.02 respectively and with corresponding burner capacities of 560 kW and 900 kW. A major experimental trial has been performed in order to validate the results and reasonable consistency has been observed. The predicted results, with particular focus on the temperature distribution and heat transfer rate of two cases have been studied in detail.Flameless-oxyfuel;soaking pit furnace; heat transfer IntroductionCondition of soaking process, including the uniformity of temperature profile and heat transfer rate plays an essential role in the total energy consumption, final quality of soaking process and pollution production in the chain [2]. Simulation of industrial combustion systems involving multiple burners using CFD modelling is still a challenging problem. Integrating burners with jet scales in order of a few inches within a large domain in order of 10 to 1000meter is still a complex problem [5]. Increment of demanding rate for high quality steel in higher volume together with recent energy and pollution crisis brings up the necessity of a constant effort for development of existing facilities and optimizations. Regarding this new technology of Flameless-oxyfuel combustion has been introduced in 90s. In this study, the effect of the combustion chamber's configuration on the characteristics of flow and combustion parameters has been investigated for a multi injecting, LPG in a real-size soaking pit furnace, using CFD simulation.