In the laboratory incubation, the effects of different biochars (maize straw biochar, rice husk biochar) and application rates (0%, 1% and 4%, m/m) on N₂O emissions and nitrification-denitrification functional gene abundances under different soil moistures (40%WHC and 100%WHC) were investigated by soil microcosm experiment in a typical black soil region in Lishu County, Jilin Province. The results show that soil N₂O emissions tends to decrease with increasing straw biochar. 4% straw biochar addition results in only 33.9% of soil N₂O emissions as compared to 1% biochar addition. Soil NO₃^--N also shows a similar pattern, significantly lower at 4% biochar addition than at 1% biochar addition. Under 100%WHC, maize straw biochar significantly increases soil N₂O emissions, while rice husk biochar significantly reduces soil N₂O emissions. Real-time fluorescence quantitative PCR further confirms that high soil moisture promotes soil denitrification by increasing nirS gene abundance, while nosZ gene abundance is significantly higher under 4% rice husk biochar addition than maize straw biochar addition, showing greater N₂O reduction capacity. Although the amoA-AOA genes are insignificantly different at different biochar additions, the amoA-AOB gene is significantly decreased at high maize straw biochar addition. Soil moisture content, biomass char species and their addition amount affect soil N₂O emissions by affecting soil nitrification and denitrification microorganisms.