At a fully mechanized working face of a coal mine as prototype, we investigated, by simulation, the flow field and dust distribution during the process of its isolation by a curtain of air, using the CFD software,Fluent. The results show that the air curtain installed on the shearer can effectively prevent the dust (especially the respirable dust) from diffusing into the work area of the operator, reducing the dust concentration on the side of the operator and greatly improving his working environment The field application of the air curtain shows that the dust-isolation effect of an air curtain is quite noticeable. The isolation efficiency for respiratory dust is over 70% and, as well, it has good dust-isolation effect for nonrespiratory dust. The air curtain is a useful way to resolve the problem of dust-isolation at a fully mechanized working face. It has a practical background elsewhere with more extensive applications.