Ammonia is the most harmful ingredient in the foul odor, which causes stress response, lowered immunity, diseases, death of livestock, and poultry poisoning. To reduce ammonia emission from chicken manure, a strain of ammonia nitrogen-degrading bacteria was isolated from chicken cecum on anaerobic nitrification medium and aerobic denitrification medium. The capacity of bacteria to degrade ammonia nitrogen was also studied. The strain was firstly identified as Bacillus megaterium via physiological and biochemical characteristics, morphological observation, and 16S rDNA sequence analysis. The content of ammonium nitrogen in chicken manure was decreased, especially at 96 h (P < 0.05), which was detected by the indophenol blue method. Correspondingly, the content of nitrate nitrogen detected... by phenol disulfonic acid method was increased and reached to the highest at 48 h (P < 0.05). In addition, the ammonia content was significantly reduced when drinking water contained 1 × 106 CFU/ml of Bacillus megaterium. In conclusion, a new bacterial strain derived from chicken cecum was identified and studied on its deodorization function in detail to provide the first direct evidence for improving environment of the chicken coop and surroundings.