Objective The ammonia level in air and heavy metals in drinking water were explored in a cynomolgus monkey feedlot. Methods Air ammonia from different communities and feeding patterns of cynomolgus monkeys were collected at three time-points per day and determined by Nessler’ s reagent spectrophotometry. Inductively coupled plasma mass spectrometry was applied to detect the level of heavy metals in drinking water from 5 different sampling sites in the feedlot, incluing the outlet of underground water, the water tank, both monkey cages equipped with PVC or iron pipes and sewage lagoon, respectively. Results Air ammonia levels in quarantine inspection flock cages (0.59 ± 0.03 mg/ m3 )were significantly higher than in the cages of both reproductive flock (0.34±0.03 mg/ m3 ) and sale flock (0.27±0.04 mg/ m3 ). The ammonia level in air in different feeding patterns ranks as following: cage rearing of quarantine inspection flock (0.59± 0.03 mg/ m3 ) > cage rearing of reproductive flock (0.48±0.02 mg/ m3 ) > captive bleeding of sale flock (0.30±0.02 mg/m3 ) > cage rearing of sale flock (0.25±0.01 mg/ m3 ) > captive bleeding of reproductive flock (0.22±0.02 mg/ m3 ). The air ammonia concentrations of both former flocks were statistically higher than the latter three flocks. The highest air ammonia level among different flocks and feeding patterns occurred in the morning, before waste discharge clean-up. The iron concentration in drinking water in the cages equipped with iron pipes was higher than Chinese drinking water standard. Conclusions The air ammonia level was lower than the Chinese air quality standard. The iron concentration in drinking water in the cages equipped with iron pipes was higher than the Chinese drinking water standard.