A 3×2 factorial design of microcosm experiment was conducted to investigate the interactive effects of straw, nitrogen fertilizer and bacterivorous nematodes on soil microbial biomass carbon (C_mic) and nitrogen (N_mic), dissolved organic carbon (DOC) and nitrogen (DON), mineral nitrogen (NH₄⁺-N and NO₃^--N), and greenhouse gas (CO₂, N₂O and CH₄) emissions. Results showed that straw amendment remarkably increased the numbers of bacterivorous nematodes and the contents of C_mic and N_mic, but C_mic and N_mic decreased with the increasing dose of nitrogen fertilization. The effects of bacterivorous nematodes strongly depended on either straw or nitrogen fertilization. The interactions of straw, nitrogen fertilization and bacterivorous nematodes on soil DOC, DON and mineral nitrogen were strong. Straw and nitrogen fertilization increased DOC and mineral nitrogen contents, but their influences on DON depended on the bacterivorous nematodes. The DOC and mineral nitrogen were negatively and positively influenced by the bacterivorous nematodes, respectively. Straw significantly promoted CO₂ and N₂O emissions but inhibited CH₄ emission, while interactions between nematodes and nitrogen fertilization on emissions of greenhouse gases were obvious. In the presence of straw, nematodes increased cumulative CO₂ emissions with low nitrogen fertilization, but decreased CO₂ and N₂O emissions with high nitrogen fertilization on the 56^th day after incubation. In summary, mechanical understanding the soil ecological process would inevitably needs to consider the roles of soil microfauna.