To identify molecular markers for early diagnosis and new targets for treatment of cervical squamous cell carcinoma. Our study involved 52 carcinoma tissues that were confirmed pathologically as cervical squamous cell carcinoma (CSCC) at the Fourth Hospital of Hebei Medical University in 2021. We obtained 36 control specimens from patients who had undergone hysterectomy for benign uterine diseases in 2021, with no cervical lesions as confirmed by pathology. Total RNA was extracted from all the samples. Reverse transcription and quantitative real-time PCR were performed. Immunohistochemical staining for interferon-stimulated gene 15 (ISG15) protein was performed. Descriptive analyses including mean and standard deviation were used to compare different groups. For data that do not conform to normal distribution, we use Wilcox rank sum test to make statistics to compare different groups with the median and interquartile. Mann Whitney U test was used to compare non-parametric continuous data, and categorical variables were analyzed using chi-square test. Receiver operating characteristic (ROC) curve was used to evaluate the possibility of using ISG15 as a new biomarker for cervical squamous cell carcinoma. Compared with normal cervical tissues, mRNA expression of ISG15 in cervical cancer tissues was significantly lower (P<0.01); mRNA expression was significantly lower in patients with nerve invasion (P<0.05). Difference in ISG15 protein expression was statistically significant (no expression/low expression) in the cancer samples compared to normal tissues (P<0.01). The area under ROC curve was 0.810 (P<0.001) and the sensitivity and specificity were 75% and 54%, respectively. Spearman's correlation analysis showed that ISG15 mRNA was positively correlated with protein expression (r=0.358, P=0.001). Deficiency of ISG15 may be associated with the occurrence and progression of CSCC. It could be used as a potential tumor marker in research and treatment of CSCC.