Abstract: By CFD numerical simulation technology of 3D visualization, we simulate gas transport in goaf under U+I type ventilation and U type ventilation. Though UDF interface, we establish gas seepage calculation model of residual coal in goaf and gas dispersion migration calculation model in mining roadways based on moving coordinate, and quantitatively analyze the difference of gas emission in gob of advancing speed and air distribution quantity of different working faces under two kinds of ventilation model. The results show that gas concentration in air return laneway under U shape ventilation system is two times than that under U+I shape ventilation system; with the increase of working face advancing speed, gas concentration in air return laneway under U shape and U+I shape ventilation systems decreases in damping form. With the increase of working face advancing speed, gas concentration under U shape ventilation system in air return laneway increases in damping form and gas concentration under U+I shape ventilation system in air return laneway increases in approximate linear form. Gas concentration in the upper corner under U+I shape ventilation system can reduce 25% to 50%.