As a metalloid element, Arsenic (As) is widely distributed in the natural environment. Its ingestion can cause cancer, deformities, and mutations. Therefore, it has become an important environmental problem in recent years. There are large amounts of arsenic ore and coal with high arsenic content in Southwest China, a karst area. There, arsenic occurs in wastewater from mines contaminate soil, vegetation, and surface water. Karst underground aquifers are also contaminated through pipes, cracks, scuttles, and sinkholes, leading to a more serious arsenic pollution problem than in non-karst areas due to the unique karst hydrogeological conditions. To prevent and curb karst underground water contamination and guarantee water resource security and public health, a review on the arsenic contamination in the karst area is necessary. This paper discusses the progress of geochemical studies on arsenic. Through an analysis of the hydrogeology of karst areas, this paper proposes that studies on arsenic pollution in karst regions should be combined with the spatial distribution and redox characteristics of groundwater. More attention should be paid to chemical compositions of water, soil, and rocks as well as adsorption-desorption processes between water and sediment when conducting arsenic geochemical research in karst groundwater.