BackgroundCircHECTD1 (circ_0031450) is highly expressed in hepatocellular carcinoma (HCC) tissues and may act as an oncogene. Its specific competitive endogenous RNA (ceRNA) mechanism remains to be further elucidated. MethodsSeveral databases and online platforms, including pathway activity, immune checkpoint, and overall survival analyses, were used to predict targets, download datasets, and perform online analyses. The R software was used for differential gene expression analysis, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), clinical relevance, receiver operator characteristic curve, and single-cell analysis. Cytoscape software was used to construct ceRNAs, protein-protein interactions (PPI), and pivotal networks. ResultsThe ceRNA, PPI, and pivotal networks were successfully constructed. Pathway enrichment analysis was mainly related to apoptosis, cell cycle, and epithelial-mesenchymal transition (EMT) pathways. Six pivotal targets related to survival, immune infiltration, immune checkpoints, clinical stage, and diagnosis of patients with HCC were identified. The recovery function and pathway enrichment results were consistent with previous results. Single-cell analysis suggested that the pivotal targets were highly expressed in T cells. ConclusionWe successfully constructed a prognosis and immune microenvironment-related ceRNA network based on circHECTD1, providing new insights for diagnosing and treating HCC.