【Objective】The application of organic fertilizers in agricultural soils increases the density of earthworms. However, it remains unclear how earthworms change the fate of soil nitrogen under different fertilizer applications. 【Method】Using a pot experiment, the present study explores the effects of earthworms on soil nitrogen utilization, loss, and nitrogen transformation processes under the application of chemical (urea) and organic (compost) fertilizers. 【Result】The results showed that earthworms significantly increased the fresh weight of plants and the amount of nitrogen uptake by plants by 12.14% and 15.24% under chemical fertilizers and 18.38% and 37.28% under organic fertilizers, respectively. Earthworms significantly increased the cumulative soil N?O emissions and the cumulative soil ammonia volatilization only under the application of chemical fertilizers. There was no significant difference in nitrogen leaching loss between the treatment with and without earthworms. Overall, earthworms increased the nitrogen loss by 6.31 and 1.69 mg·pot?1 under the application of chemical and organic fertilizers, respectively. Also, earthworms significantly increased the ratio of the total nitrogen utilization by plants to the total nitrogen loss under the application of organic fertilizers, but no significant difference was found under the application of chemical fertilizers. The soil nitrogen primary transformation rate model showed that earthworms affected more nitrogen transformation processes under the application of organic fertilizers than under the application of chemical fertilizers, significantly increasing the total primary nitrogen mineralization rate of the soil. 【Conclusion】Regardless of the type of fertilizer applied, earthworms played a dual role in promoting plant nitrogen utilization and increasing nitrogen loss. However, considering the ratio of nitrogen utilization to loss, the application of organic fertilizers provided a more conducive environment for achieving the beneficial effects of earthworms in the soil nitrogen cycle.