Our aim was to study the expression of human SET domain containing protein 1A (hSETD1A) in hepatocellular carcinoma patients and its relationship with human hepatocellular carcinoma cell function. A total of 30 patients with hepatocellular carcinoma were enrolled in this study. The expression of hSETD1A was detected by real-time polymerase chain reaction (PCR) and Western blotting. The immortalized normal human liver cell line including SMMC-7721 was subjected to real-time PCR for hSETD1A mRNA. Furthermore, hSETD1A-small hairpin RNA (shRNA) was used to knock down hSETD1A expression in SMMC-7721 cells. Cell proliferation, cell apoptosis, and cell migration were determined by CCK8, flow cytometry, and Transwell assays. The positive expression rate level of hSETD1A mRNA and protein in liver carcinoma tissues was 73.33%. hSETD1A knockdown using a specific hSETD1A-shRNA inhibited cell proliferation and promoted cell apoptosis in SMMC-7721 cells. It was also found that downregulation of hSETD1A inhibited cell migration ability but did not affect cell invasion. In conclusion, the expression of hSETD1A occurs at a high rate in hepatocellular carcinoma patients. The expression state of hSETD1A may be a prognostic factor in hepatocellular carcinoma.