Ammonia volatilization not only causes nitrogen loss from agricultural soil，but also aggravates atmospheric haze pollution.It remains unknown about the effects of elevated carbon dioxide(CO₂) concentration and climate change on ammonia volatilization from the agricultural soil.The effects of elevated CO₂ concentration，either gradual increase or abrupt increase by 200 mg/L，on ammonia volatilization from rice wheat rotation field in southern China were investigated through OTC(open top air chamber) simulation.The response of ammonia volatilization from rice-wheat rotation field was simulated with the continuous increase of CO₂ concentration by the end of this century.This study investigated the ammonia volatilization from rice-wheat field under three CO₂ treatments，including ambient CO₂(CK)，gradual increase in CO₂(T1) and abrupt increase in CO₂(T2).The ammonia volatilization in farmland was determined by vented chamber for trapping.The results showed that:(1)After two years of field experiment，the cumulative ammonia volatilization was 7.87 kg/hm² in wheat field and 80.38 kg/hm² in rice field under elevated CO₂ concentration.Ammonia volatilization in the wheat season was relatively low，and the annual ammonia volatilization was mainly contributed by the rice season. (2)Ammonia volatilization in the wheat season lasted longer，and the volatilization peak was closely related to the precipitation.The peak of ammonia volatilization in the rice season was found in 1 to 4 days after fertilization and persisted for a short period of time，then declined to the background value in 2 weeks.(3)The main factors affecting ammonia volatilization in this study were air temperature，precipitation and soil ammonium nitrogen concentration.(4)There was no significant difference in the volatrle ammonia volatilization of 2018 winter wheat，2019 rice，2019 winter wheat and 2020 rice.Therefore，it is can be preliminarily inferred that there is nearly no significant impact on the ammonia volatilization from rice-wheat field，even if the CO₂ concentration increase by 200 mg/L by the end of this century.