Activated carbon fiber was oxidized through nitrocellulose combustion below 300℃ to introduce oxygen-complex on its surface. The pore structure, elemental composition, chemical functional groups of activated carbon fiber before and after oxidized were investigated. The result showed that the oxygen-complex could be efficiently introduced after nitrocellulose combustion; especially for the imide; and the micropore diameter was slightly wider after oxidization. It provided a simple method to introduce oxygen-complex using nitrocellulose combustion. The activated carbon fiber oxidized by nitrocellulose combustion displayed higher adsorption capacities for ammonia and carbon disulfide than that of the original activated carbon fiber due to the introduced oxygen-complexes.