Based on a six-year field experiment, the effects of irrigation lower limits (soil water suction of 25, 35 and 45 kPa, marked as W₁, W₂ and W₃ respectively) and nitrogen fertilization rates (75, 300 and 525 kg N/hm², marked as N₁, N₂ and N₃ respectively) on soil ammonia volatilization flux, cumulative volatilization, tomato yield and ammonia per unit yield cumulative emission were studied in greenhouse by the high-resolution laser spectroscopy. The results showed that the peak of ammonia volatilization flux, cumulative volatilization, ammonia volatilization accumulation, ammonia volatilization loss rate and tomato yield were significantly affected by the irrigation lower limits, nitrogen fertilization rates and their interactions. The peak of ammonia volatilization flux occurred after 6~8 days of nitrogen application. The empirical sigmoidal model could be used to well fit the changes of ammonia volatilization accumulation with time in the basal and topdressing periods. The model parameters of ammonia volatilization were mainly affected by the irrigation lower limit and its interaction with nitrogen in the basal period, and which was mainly affected by nitrogen fertilization and its interaction with irrigation in the topdressing period. Drip fertigation could significantly reduce ammonia volatilization by 94.78%~96.30% compared with the basal fertilization. The nitrogen loss rate of ammonia volatilization ranged from 0 to 2% under the influence of soil pH, soil NH₄⁺-N content and nitrogen fertilization zone proportion. Considering the mitigation of ammonia volatilization and increase of tomato yield, it was concluded that the optimal management in greenhouse was W₁N₂ treatment.