Ammonia emission is one of the important pathways of nitrogen fertilizer loss from farmland in the Taihu Lake region. In order to study ammonia emission dynamics and influencing factors of paddy field in the Taihu Lake region, the TDLAS-BLS method with high-temporal resolution was used in this experiment. The results showed that, compared with the night time, the concentration and variability of ammonia above the rice canopy were significantly higher in daytime after fertilization. Ammonia emission increased rapidly, reached a maximum value in 2–3 days after fertilization, and then decreased rapidly. Ammonia emission loss in tillering stage (36.6%) were higher in panicle stage (23.0%), which was mainly concentrated in the initial four days after fertilization, and accounted for 80% and 84% of total ammonia losses for tillering and panicle stages, respectively. In tillering stage, wind speed, solar radiation and air temperature obviously promoted ammonia emission, and solar radiation influenced most. The effects of wind speed and temperature on ammonia emission in panicle stage were low. Precipitation significantly decreased ammonia emission rate, and was the main factor influencing ammonia emission during the rainfall.