Objective To analyze and screen key genes affecting the prognosis of cervical cancer based on bioinformatics, and to explore their functions. Methods The microarray datasets of cervical cancer (GSE6791, GSE39001, GSE55940 and GSE63678) were downloaded from Gene Expression Omnibus (GEO) database, and the differentially expressed genes (DEGs) were screened after merging and batch normalization. The DEGs were analyzed by gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analyses and protein-protein interaction (PPI) network, and survival analysis was performed based on The Cancer Genome Atras (TCGA) database to identify key genes. The functions of key genes were analyzed by gene set enrichment analysis (GSEA), and the pan-cancer data based on TCGA database were used for in-depth research on functions, including gene correlation analysis, univariate Cox regression, immune subtype, tumor microenvironment and tumor stemness. Results A total of 336 DEGs were screened out, of which 153 were down-regulated and 183 were up-regulated. Mini-chromosome maintenance protein 2 (MCM2) was selected as a potential biomarker for cervical cancer by PPI network and survival analysis. The results of GSEA suggested that MCM2 was associated with autophagy and mitogen-activated protein kinase signaling pathway. The research in pan-cancer showed that the expression of MCM2 was positively correlated with the 5-year overall survival rates of 4 cancers (cervical cancer, lymphoid neoplasm diffuse large B-cell lymphoma, rectum adenocarcinoma, and uveal melanoma) and negatively correlated with 7 cancers (adrenocortical carcinoma, kidney chromophobe, acute myeloid carcinoma, brain lower grade glioma, liver hepatocellular carcinoma, mesothelioma and sarcoma). The research on functions in pan-cancer data suggested that MCM2-10 were invoved in the immune subtypes of cancers; tumor tissues with high expression levels of MCM2-10 had low proportions of matrix cells and immune cells and a high proportion of cancer cells; and the expression level of MCM2 was positively correlated with the tumor stemness in many cancers. Conclusion MCM2 is highly expressed in cervical cancer and related to the prognosis of patients, making it a potential biomarker for prognosis of cervical cancer. Furthermore, MCM2 is involved in various biological processes of many cancers, and it serves as a new target for cancer therapeutic intervention.