Entrained flow gasifiers that may operate in an upflow or downflow manner widely used for coal gasification reactor in Intergrated Gasifiaction Combiend Cycle(IGCC) power plant. In this Study Computational Fluid Dynamics(CFD) simulation of commercial-scale entrained-flow gasifiers was conducted to study the inside flow behavier of entrained flow gasifiers. The numerical model used in this study is composed of Lagrangian particle tracking model, volatilization model, char gasification model, and gas phase reaction with Arrhenius rate kinetic reaction and solved by FLUENT. The numerical simulations with developed coal gasification model were performed on commercial-scale one-stage upflow and single-stage downflow gasifiers. Based on simulation results, the comparision of flow characteristics was investigated for the two different entrained flow gasifiers.