Abstract: In order to obtain the reasonable design parameters of the dust-isolating air curtain in working face, enhance the dust-isolating efficiency and improve the working environment, the 1240 fully mechanized working face of the No.8 Mine of Pingdingshan Coal Co., Ltd was studied as the background. By using hydromechanics software Fluent6.3, the air flow field in fully mechanized working face and the dust concentration distribution on both sides of the air curtain was simulated numerically for different outlet wind velocity and width of the air curtain respectively. Thus the parameters were determined while analyzing the best dust-isolating effect of the air curtain. The results showed that for this working face, the dust-isolating effect of the air curtain was best when the outlet wind speed was 4 m/s and the outlet width was 30 mm, and the dust concentration was minimum on driver side.