In order to mitigate CO2 emissions from steel industry, decreasing coke rate by establishing oxygen blast furnace ironmaking process is a favorable way. Yet every improvement in productivity is fundamentally related to better flow distribution of gas across a particle bed and hence total pressure drop in granular zone is a leading parameter affected by interfacial resistance between alternating layers of coke and metallic burden. In this work, the existence and change rule of interface resistance with different parameters such as flow rate, interface numbers, layer thickness are confirmed. A new pore-throat equation proposed by J.S. Wu and B.M. Yu [30] is imported to study pressure drop of gas flow through stock column in blast furnace and compared with well-known Ergun's equation. Furthermore, the relationships between interface resistance and physical parameters involved in this study is explored and combined with this new pore-throat equation to be a new modified equation. Meanwhile, its adaptability is verified for various conditions. On the basis of modified equation, interfacial porosity with flow rate is discussed and linked to microphenomenon of previous work and achievement of other researchers. (C) 2013 Elsevier B.V. All rights reserved.