Emerging nitrogen-containing disinfection by-products have lower concentrations than conventional disinfection by-products but are more toxic and more difficult to remove. This study proposes to use activated carbon to remove the precursors that form nitrogen-containing disinfection by-products take tryptophan as an example compare the removal performance of conventional and new activated carbons for precursors and explain the mechanism. The study found that the maximum isotherm adsorption capacity of powdered activated carbon PAC and activated carbon fiber ACF for tryptophan were 37. 31 and 178. 57 mg?? g-1 respectively and the adsorption rates of tryptophan were 5. 95 × 10-2 sec-1 and 1. 7 × 10-3 sec-1 respectively. The adsorption of tryptophan on both types of activated carbon belonged to the Langmuir model r2 ≥0. 99 and the adsorption kinetics were both pseudo-second-order kinetic models. ACF had a larger specific surface area a larger total pore volume a smaller average pore size and more surface functional groups than PAC. In the range of 15 ℃ ~45 ℃ ACF and PAC were both entropy-driven spontaneous adsorption of tryptophan and the adsorption driving force first increased and then decreased but the adsorption of tryptophan by PAC and ACF is physical adsorption and chemical adsorption respectively. The research results show that because the molecular weight of the precursors of the nitrogen-containing disinfection by-products is generally small ACF is more suitable for the removal of its precursors. Because the ACF has a smaller pore size and a slower adsorption rate it is necessary to ensure sufficient adsorption contact time.