This study was numerically and experimentally investigated on improvement capture velocity for increasing inhalation efficiency of hood in local ventilation system. The inhalation efficiency of hood was studied to improve by increasing inhalation force of the hood that attached the new device named “Gas-Guide-Device (GGD)”. Also, harmful material that couldn’t inhale in hood was removed by increasing capture velocity at the edge of hood. For the numerical study, computational fluid dynamic (CFD) was used to predict the improvement of flow velocity with attached GGD in hood. To verify the numerical result, the flow velocity was experimentally measured using a hot-wire type anemometer. As a result of the numerical and experimental study for improving the effect of the GGD on the inhalation efficiency of the hood, it was verified that the capture velocity around the hood inlet was relatively higher for the hood with the GGD than for the one without it.