Abstract: The adsorption of amoxicillin (AMX) in aqueous solution on activated carbon modified with hydrogen nitrate was investigated under different conditions, and the adsorption kinetics and adsorption isotherm models of activated carbon adsorbing AMX in aqueous solution were explored based on variation of adsorption time and initial AMX concentration. The results showed that the adsorption equilibrium time for initial AMX concentration of 50.0 mg/L and 200.0 mg/L, respectively was nearly 60 min with 0.100 0 g of activated carbon, and there had a well adsorption percentage when the initial pH of AMX solution was at 4-6. The adsorption percentage and the adsorption quantity were 78.79% and 71.4 mg/g, respectively, under the optimum condition of 193.7 mg/L of initial AMX with 4.05 of pH, 60 min of adsorption time and 0.100 0 g of activated carbon modified with HNO3. Freundlich adsorption isotherm could be used to describe the adsorption of AMX on activated carbon and the adsorption of activated carbon adsorbing AMX in aqueous solution was well fitted to the pseudo-second kinetics.