Earthworms play an important role in determining the greenhouse-gas balance of soils worldwide. A field experiment in aerobic rice was conducted to investigate the effects of crop residues and earthworm activities on soil properties and N2O emissions. A 120-day mesocosm experiment was set up in which crop residues were either incorporated or applied on top of the soil in the presence or absence of earthworm (Metaphire guillelmi). The results indicated that Metaphire guillelmi significantly enhanced soil N2O emissions. In the treatment with crop residues mulching, the cumulative emission amounts of N2O significantly increased from 12.54 to 14.94 kg/hm2 (P<0.05) in the presence of earthworm. However, if residues were incorporated into the soil, the earthworm effect disappeared. Soil mineral nitrogen was increased, and nitrogen mineralization was strengthened by earthworm activities. The level of NH4+-N in soil of different treatments remained at a very low level during the whole growing period of aerobic rice, while the variations of NO3--N content in soil was very high. The spatial-temporal variations of soil NO3--N had close relationships with soil mineral nitrogen level. The results of this study suggested that Metaphire guillelmi increased cumulative N2O emissions by affecting denitrifier community activity via incorporation of fresh residue into the soil and accelerating decomposition.