Abstract: This study aims to explore the effect of the phosphoric acid-microbial agents on the reduction of ammonia emissions from liquid slurry. Phosphoric acid and lactic acid bacteria were taken as the research objects. A series of experiments was also carried out on the acidifier-coupled biological agents to inhibit nitrogen loss in liquid slurry. A systematic analysis was then made on the effect of the acidifier-microbial agents on the physical and chemical properties and nitrogen reduction during manure storage. The pH value of fresh manure was adjusted to 6.5 with phosphoric acid. Microbial agents were added to the manure in order to analyze the variations in the ammonia emissions, nitrogen transformation, and microbial communities in the manure. An investigation was also implemented to explore the effect of phosphoric acid-microbial agents on the reduction of ammonia emissions during the storage of liquid slurry. Three treatment groups were set in this experiment: CK was the control group, T1 was the group with only phosphoric acidifier to acidify the manure water, and T2 was the group with phosphoric acidifier and microbial agent to treat the manure water. The experiment was carried out in the laboratory of the Planning and Design Institute of the Ministry of Agriculture and Rural Affairs (Shuangqiao Campus). The experimental breeding manure was taken from a pig farm in Beijing. The experimental period was 60 days. The manure pH value, EC, NH₃, ammonium nitrogen, nitrate nitrogen, organic nitrogen, seed germination index, volatile acid, and other indicators were measured on the 0th, 7th, 14th, 21st, 35th, 49th, and 60th days. The manure TS and VS indicators were measured on the 0th, 15th, 30th, 45th, and 60th days. The microbial diversity of manure was detected on the 0th, 30th, and 60th days, in order to analyze the effect of the bacterial agents. Ammonia emissions were reduced from the acidified liquid slurry. The results showed that the phosphoric acid-microorganism co-treatment of manure water reduced the cumulative emission of NH₃ by 28.81%, compared with the control group (CK), and by 17.03% when phosphoric acid was added alone (T1). The total nitrogen loss rate was reduced by 2.25%, compared with the CK, and by 5.11% when phosphoric acid was added alone (T1). The total production of VFAs increased by 21.61% and 30.91%, respectively, compared with the CK and phosphoric acid added alone. Among them, Leucobacter and Sphaerochaeta in the acidified manure water group (T1) were positively correlated with the VFAs and NH₄⁺. While the Terrisporobacter was negatively correlated with NH₃. The main functional bacterial genus for acidified manure water produces the VFAs and inhibits ammonia. Therefore, it is very feasible to construct a two-stage liquid manure ammonia emission reduction using phosphoric acid-Leucobacter, phosphoric acid-Sphaerochaeta, and phosphoric acid-Terrisporobacter. In summary, the phosphoric acid and microbial agents were selected to reduce the liquid manure ammonia. The acidifier was used to inhibit ammonia reduction in the early stage of manure storage through chemical action. And then the microbial agent was to inhibit ammonia reduction in the middle and late stages of manure storage through biological action. The finding can provide technical support for green agriculture.