Abstract: Composting is one of the effective means to recycle livestock and poultry waste, but the loss of nitrogen during the process leads to a decrease in composting product quality. Moreover, ammonia (NH₃) and nitrous oxide (N₂O) emissions will aggravate air pollution and the greenhouse effect. To reduce the emission of reactive gaseous nitrogen during composting and improve the nitrogen content of composting products, pig manure and chicken manure were selected as raw materials for indoor simulated composting. The experimental treatments included inoculation with Bacillus strains, amendment with chemical additives, and combining Bacillus strains with chemical additives. The results show that the treatment with chemical additives only or a combination of Bacillusstrain with chemical additives significantly decreased the emission of reactive gaseous nitrogen and maintained nitrogen in composting product compared with dual non-inoculated and non-amended control. In the process of pig manure composting, the NH₃ emission was decreased by 11% to 21% in treatment with chemical additives only, or dual treatment with Bacillus sp. H3-1 and chemical additives, and dual treatment of B. sp. H5-9 with chemical additives in comparison with the control. It was also observed that N₂O emission decreased by 4%-6% in these treatments compared with the control. The content of NH₄⁺-N in composting products increased by 6.7-7.7 times compared to the control. In the composting process of chicken manure, the N₂O emission was decreased by 25%-26% in the treatment with chemical additives only or dual treatment with B. sp. H1-10 and chemical additives compared with dual non-inoculated and non-amended control. The NH₄⁺-N content of composting products increased by magnitude of 3.3-3.9. Therefore, the amendment with chemical additives only or a combination of Bacillus strain with chemical additives could reduce NH₃ and N₂O emissions and maintain the nitrogen in composting products simultaneously. This study adds valuable information and provides a fundamental scientific knowledge towards the green and efficient resource utilization of livestock and poultry manure and help in achieving agricultural carbon neutrality.