A simulated experiment in laboratory was conducted to study the ecotoxicological effects of tetracycline (TC) on the growth, antioxidant defense system and the gene expression of earthworm Eisenia foetida in soil. The results showed that, in the early exposure (≤14 d), the weight and soluble protein (SP) of earthworm stressed by 1-100 mg·kg^-1 TC had no significant difference from the control. However, with the increase of TC concentration and the prolonging of exposure time, the weight of earthworm decreased and the content of SP increased. The balance of the antioxidant system was destroyed by 1-100 mg·kg^-1 TC with the activities of SOD, POD and CAT increased to varying degrees after a 14 d exposure. Moreover, the results of DDRTPCR showed that 1-100 mg·kg^-1 TC affected the gene expression of earthworm after a 28 d exposure. It was suggested that TC had chronic ecotoxicological effects on earthworm and the biomarkers such as antioxidant defense enzyme and the gene expression can be used to estimate the ecotoxicological effects of TC.