Abstract: The toxicity of arsenic has been well known since ancient times for the noxious white arsenic. Furthermore, arsenic has been listed in the first group of carcinogens by the Association for International Cancer Research (AICR). Nowadays, millions of individuals in the world are suffering from by arsenic toxicosis and the arsenic contamination has been reported worldwide. The origin of arsenic in environment is rather complex and originated from natural processes（mainly for geological process）, or anthropogenic activities, or combination of both. Moreover, arsenic can transfer and transform through different natural geochemical and biological processes，therefore will directly or indirectly harm to people and animals, etc.. In this paper, a comprehensive discussion on arsenic issue is presented, including its origin and distribution, its mobility and transformation，toxicity and impacts on living things, as well as recent progresses on arsenic research. Arsenic contamination and toxicosis in some regions such as Inner Mongolia in China are very serious now, so the research on arsenic geochemistry and impacts on human health from arsenic are tough and meaningful job.