Abstract: Adsorbent was prepared from Cyperus alternifolius as the raw material, and the removal effects of ammonia nitrogen adsorption time, dosage, adsorption temperature, pH and particle size in different concentrations of carbonized Cyperus alternifolius were studied. Fourier Transform Infrared was used to detect and analyze the variation of functional group before and after the treatments of ammonia nitrogen. The experimental results show that: with increasing carbonization time, carbonization temperature, ammonia nitrogen removal rate reached maximum of 100%. The optimum conditions were: the adsorption time 60 min, adsorbent dosage 1.50 g, adsorption temperature 30, pH 6~8 and water bamboo particle size 420~841 m. The results of Fourier Transform Infrared showed that abundant hydroxyl radical and amino -groups were found in carbonized Cyperus alternifolius, which reacted with ammonia nitrogen in wastewater to remove it.