Recently, the present working environment tends to be reconsidered with high interest in the environmental problem. Especially, air pollution by generating metallic fume during the progress of cutting and welling is the unavoidable issue for labor health. For settling this matter, it is necessary to design the suitable ventilation system that is desirable to be generally composed of large scaled equipments with high efficiency due to big capacity of a fabrication shop. However, the physical property and movement characteristic of fume as minute particles have not been grasped accurately even now. In this paper, with a view to establishing the ventilation system with perfect control of fume flow, the transportation phenomena on fume, that are assumed minute particles to be gas-phase in turbulent flow by driving vent fans, would be clarified using experimental means and numerical calculation. The experimental simulations of fume diffusion using smoke generator in the three dimensional models of fabrication shop are executed with the appropriate similarity law. And the experimental result of fume flow shows considerably good agreement with the calculated data using two-layers Zone model on the diffusion state of heat and fume. Furthermore, the relation between the ventilation system and the fume transportation state in a fabrication shop is investigated evidently using experimental data.