| (Objective)High arsenic groundwater in Hasuhai area poses a serious threat to the safety of drinking water for local residents. Revealing its formation and evolution mechanism is of great significance to the scientific and rational development and utilization of water resources and the protection of residents' health. (Method) In this paper, based on hydrogeologic investigation, Piper diagram, arsenic speciation calculation of PHREEQC and correlation analysis are used to research the high arsenic groundwater. We studied hydrogeochemical characteristics and constructed the arsenic speciation model (SM) and Arsenic adsorption model (HSM) to reveal the genetic mechanism of high arsenic groundwater. (Results) The results showed that arsenic concentration vary between 0.2 μg/L to 231.5μg/L, and high arsenic groundwater is mainly distributed in the alluvial plain south of Daqingshan Mountain. As(Ⅲ) is the main type of arsenic in shallow groundwater in the study area, SM shows that the dominant form is H3AsO3, and HSM shows that there are two main forms of arsenic: H3AsO3and Hfo_wH2AsO3. (Conclusion)Arsenic in groundwater may come from the dissolution and weathering of surrounding arsenic-rich rocks and quaternary arsenic-rich fluvial and lacustrine sediments. The fluvial and lacustrine sedimentary environment in the study area is the prerequisite for the formation of high arsenic water, and the weak alkaline reduction environment dominated by the decomposition of organic matter is the main factor leading to the transfer of arsenic from aquifer to groundwater, and the competitive adsorption of HCO3-also promotes the release of arsenic.