The adsorption mechanism of methylene blue onto silver-loaded activated carbon fiber is different from those by Langmuir and Freundlich models. In this paper, an adsorption isotherm model is established with two parameters to describe na-nosilver impact and load amount of silver nanoparticles, respectively, on adsorb-ability. In the process, the absorbance value of equilibrium solution was meas-ured by spectrophotometry, and thus equilibrium concentrations and equilibrium adsorption quantity were calculated. The model was determined according to the fitting curve and comparison was made between the theoretical prediction and experimental data, showing relative good consistence.