Abstract: Chromium is an essential trace element in human body, and its ion valence state is closely related to its effect on human body. Trivalent chromium is the most stable state of chromium in nature. It can be used as a co-factor of insulin to regulate the metabolism of sugar, fat and protein, and has no epigenetic toxicity to human body. Howerver, hexavalent chromium, a carcinogen, poses a serious threat to human health by interfering with epigenetic patterns such as DNA methylation, histone modification, chromosomal remodeling and non-coding RNA regulation. This review is of great significance to fully understand the biological functions of trivalent chromium and the epigenetic toxicity of hexavalent chromium.