Abstract: Arsenic, a naturally occurring metal-like chemical element, is one of the 10 chemicals of major public concerns listed by the World Health Organization as harmful to the environment and human health. It can enter the human body through breathing, intaking food, drinking water, skin exposure, and other ways, and long-term exposure to arsenic can cause cancer of multiple organs and impaired function of multiple systems. Epigenetic mechanisms play an important role in arsenic-induced health effects, and research suggested that the carcinogenicity of arsenic may be associated with epigenetic changes. Previous studies focused on the effects of arsenic on DNA methylation modification. In recent years, research showed that 5-hydroxymethylcytosine (5-hmC), an intermediate of active demethylation of DNA, can act as a sensitive epigenetic mark and play a crucial role as a "bridge" between arsenic exposure and health effects. Based on the latest research progress on the role of DNA hydroxymethylation in the health effects associated with arsenic exposure, this article briefly described the relationship between the health effects of arsenic exposure and DNA hydroxymethylation, summarized the possible mechanisms of DNA hydroxymethylation in the health effects associated with arsenic exposure, and provided a scientific basis for preventing and treating the health effects associated with arsenic exposure.