Inflammation has been reported as a facilitator in cervical oncogenesis, but the correlation between inflammation and cytology abnormality including Cervical Intraepithelial Neoplasia (CIN) remains uncertain. The aim of this study was to investigate the correlation between them with ThinPrep cytological test (TCT) as a screening tool for cervical cancer and CIN, which can identify abnormal morphology of cervical mucosa epithelium and inflammation degrees. A retrospective analysis of clinical data from 48101 women undergoing TCT in the affiliated hospitals of Sun Yat-Sen University (SYSU) revealed that among the 8.87% (4102 cases) total positive rate of ASC, LSIL and HSIL, 67.7% (2777/4102) of TCT positive samples had inflammatory infection. The rate of severe inflammation was significantly higher in cytological abnormality group than the control group (15.1% vs. 2%, P=0.000). Our results showed that severe inflammation significantly increased incidence of cytological abnormality by 12.59 times and elevated the risk of HSIL by 756.47 times. In conclusion, severe inflammation increased the risk of cytological abnormality, and should be viewed as an important risk of HISL. These results of our study remind clinicians to be more watchful for women with severe cervical inflammation in TCT reports for earlier prevention of the HSIL.