This study aims to investigate the expression level of IL-8 during the rat lung squamous carcinogenesis, and to discuss the relationship with the lung cancer pathogenesis. 40 of 48 Wistar rats were instilled with the chemical agent into the left lobarbranchus to induce lung squamous cell carcinoma. The other 8 rats as in control group were instilled with iodized oil. Apical puncture haemospasia (4-6 ml) were performed before the rats being put to death in batch, the lung tissues of the perfusion parts were removed. The specimens of lung squamous cell carcinoma in each stage of the development process were obtained. Double-antibody ABC-enzyme-linked immunosorbent assay (ELISA) was used to detect serum IL-8 levels in 48 rats. In the study, 7 cases had epithelial hyperplasia, 15 cases had atypical hyperplasia, 6 cases had carcinoma in situ, 7 cases had invasive carcinoma, 6 cases had metastatic carcinoma, 7 cases were taken as normal controls. The expression levels of serum IL- the control group gradually increased with the progress of cancer. The expression levels of serum IL-8 among the hyperplasia, atypical hyperplasia and lung squamous cell groups had significant difference (P=0.018, P=0.000), while significant difference between the metastasis and the non- metastasis groups (P=0.002). This study suggested that serum IL-8 levels had close relationship with occurrence, invasion and metastasis of lung cancer, as well as great significance in the early diagnosis and prognosis.