The amount and process of ammonia volatilization from nitrogen fertilizer in the rice field of Fe leachi Stagnic Anthrosols in the Taihu Lake region were investigated.The effect of some soil factors on N loss was also studied.The purpose of the experiment was to provide basic theory to reduce the amount of ammonia volatilization loss from nitrogen fertilizer and improve nitrogen use efficiency in rice field.Ammonia volatilization loss from urea applied was measured with the continuous airflow method in the experiment and the main influencing factors (NH₄⁺-N concentration and pH in flooded water,etc.) were also measured.Results showed that ammonia volatilizat ion loss varied from 3.7% to 11 7% of applied N,the highest N loss oc curred in the period of tillering top dressing,lower in ear bearing top dressing period,and the least in basal dressing period.Ammonia volatilization primarily occurred in one week after fertilization.And there was a significant correlation between the NH₄⁺-N concentration,pH in the flooded water and the amount of ammonia volatilization (the correlation coefficient was 0.791^** and 0.443^**,respectively).