Carbon materials have a very large surface area and various surface functional groups. They have been widely used as the adsorbent alone or the modified surface to adsorb pollutants. In the process of producing of yellow phosphorus by electric furnace, about 3000 m3 tail gas will be let out for one ton yellow phosphorus production. Tail gases consist of 90% of carbon monoxide (CO) and phosphine (PH3). The PH3 prevents the highly efficient utilization of CO and is an irritant and general systemic poison. Therefore, it is necessary to study how to effectively remove PH3 in tail gases. Due to the fact that selective adsorption of non-modified activated carbon (AC) is not enough to remove PH3 with a high efficiency, modification of AC might be an attractive route to improve the adsorption capacity. In this paper, experiments were carried out to study the factors influencing the adsorption of PH3 on the modified AC such as the concentration of impregnant, reaction temperature, oxygen content and space velocity. The results showed that the 5% HCl was the optimum concentration of impregnant. In the presence of oxygen, the adsorption capacity of modified AC was more than that in the absence of oxygen. In addition, with the improvement of the reaction temperature, the adsorption capacity of modified AC was increasing initially then decreasing, because of the transition from physical adsorption to chemical adsorption as priority. The adsorption capacity of the modified AC was enhanced initially with the increasing of oxygen content. Once the oxygen content was enhanced over 1%, there was no significant increase in the adsorption capacity of modified AC. The adsorption capacity of modified AC was decreased with the increasing of space velocity. The optimum parameters of reaction were 5% HCl of impregnant, 70°C of reaction temperature, 1% of oxygen content, and space velocity 10～20min-1.