The characteristics of a gas explosion were investigated with regard to the hole/pore scale in a coal-mine gob. A 3-D hole-pore single-layer network model (3-D HPSLNM) was developed, and the effects of the length-to-diameter ratio (L/D), ignition location, and gas concentration on the explosion flame and overpressure were determined with the FLACS flame acceleration simulator (Gexcon). The flame propagation speed was positively correlated with L/D and was lower in the hole than in the pores. The overpressure increased linearly with L/D. The flame propagation shape stretched and developed in different ways depending on the ignition location. The maximum flame speed and maximum overpressure for ‘end ignition’ were 56.5% and 25.2% higher than for ‘edge ignition’, respectively. The findings of this study will help further research into the hole/pore-scale effects of gas explosions in coal-mine gobs.