The ability of composite molecular sieve to remove NH3N from water through static adsorption was studied. The effects of various factors, such as temperature, pH value, contact time consistency, on the removal efficiency during the adsorption of molecular sieve were analyzed. The results showed that, by using the composite molecular sieve with the amount of 4g and the size of less than 09mm to treat 100mL NH3N water with the concentration of 5mg/L, the NH3N removal efficiency of molecular is up to more than 80%. The contact time was propotional to the NH3N efficiency at the initial stage and reached the equilibrium state in 40min. The removal of NH3N was higher in weak acidic and alkali condition. The removal of NH3N raised with the temperature.