Large-eddy simulation (LES) coupled with the extended flamelet/progress variable approach (EFPV) has been performed to predict characteristics of reacting flows in a bench-scale hot coke oven gas (HCOG) reformer. In order to investigate the capability of capturing effects of operating conditions, simulations were carried out in two different cases in which the coke oven gas temperature and oxygen ratio were altered. Results showed that the LES coupled with the EFPV performed very well in terms of predicting temperature distribution as well as the temperature variation trend between the two cases. In addition, major species such as H-2, CO, CO2, H2O and CH4, as well as minor species like benzene and some typical polycyclic aromatic hydrocarbons (PAH) were analyzed to illustrate their activities and dominant chemical events. With regards to the composition of the dry reformed gas, comparisons were made between the experimental data and the numerical simulation results, and reasonable results have been obtained. It has been confirmed that the general feature of the reacting flows in the HCOG reformer can be precisely captured by the present LES.