In order to explore the characteristics and mechanisms of ammonia adsorption by ANAMMOX granular sludge, the ammonia adsorption characteristics by ANAMMOX granular sludge in different initial ammonia concentrations and sludge concentrations, as well as the influences of temperature, pH, salinity and metal cations on the ammonia absorption were studied respectively; moreover, the adsorption isotherms, kinetics models and thermodynamics analysis were employed to investigate the adsorption process. Adsorption equilibrium was achieved in about 20minutes; the ammonia adsorption capacity was increased with the increasement of the initial ammonia concentration, however, showed a decline trend with the increasement of ANAMMOX granular sludge concentration; low temperature was in favor of ammonia adsorption; the optimal pH was 7.0. Salinity and metal cations had an obvious affect on the ammonia adsorption: when the concentration of NaCl was 5g/L, the ammonia adsorption process was inhibited completely almost; under the same mass concentration, Fe³⁺ showed the strongest inhibition effect, Mg²⁺ and Ca²⁺ took the second place and Cu²⁺ was the weakest relatively. The ammonia adsorption process by ANAMMOX granular sludge was fitted to the Freundlich isotherm, and the adsorption process was in line with the pseudo-second-order kinetic model, moreover, was the combined results of surface diffusion and internal diffusion. Thermodynamic studies demonstrated that the adsorption process was a spontaneous exothermic process.