In order to further improve an air curtain's dust suppression performance in tunnels, this paper made an in-depth analysis of the effects of an air curtain generator's radial and axial pressure airflow rate and a dust removal fan's exhaust airflow rate on the diffusion and pollution behaviors of dust. Through CFD Technology and field measurements, it can be observed that: when the air curtain generator's axial-to-radial pressure airflow rate ratio (Ra/r) varied within the range of 1/9–6/4, the diffusion distance of high-concentration dust (with a concentration over 10 mg/m3) decreased with the decrease of Ra/r; and when Ra/r = 1/9, the formed airflow curtains exhibited the most favorable dust suppression performance. In addition: when the dust removal fan's exhaust-to-pressure airflow rate ratio (Re/p) increased, the diffusion distance of high-concentration dust decreased; and when Re/p = 1.2, the dust produced could be suppressed effectively by the air curtains. Finally, field measurements reveal that when a dust removal fan with a Re/p of 1.2 and an air curtain generator with a Ra/r of 1/9 were used in combination, high-concentration dust can be controlled fully within a range of 5.49 m from the head-on section by the formed air curtains, and the average dust concentration in the region 5–50 m away from the head-on section in tunnel was reduced to 9.82 mg/m3; i.e., the excavator driver and workers can be protected effectively.