The dynamic adsorption behaviors of benzene vapor on phosphoric acid-activated carbon fiber (ACF-P) were investigated by gas chromatography. The experimental results showed that ACF-P that was activated at >350 degreesC, like steam-activated carbon fiber (ACF-W), has good dynamic adsorption properties for benzene vapor. However, the saturation adsorption capacities of ACF-P and ACF-W are different. The dynamic adsorption conditions apparently do not affect the effluent concentration before the breakthrough point, but do change the operation loading and usage efficiency. The adsorbed ACF-P can be regenerated, and good dynamic adsorbability can be recovered by heating treatment.