This work researches the factors effected to behaviour of arsenic releasing f-rom pyrite tail after exploitatin in laboratory model scale. That were pH, metallic ions, bacteria effected to mobility of As(III) and As(V) under anoxic and oxygen present condition. The atates of arsenic and heavy metals are important factors influencing to their moving, transportation and deposition in environment and cause environmental pollution. In the oxygen condition and high pH values, As(V) ) is more dominant than As(III) and in the anoxic condition As(III) is more dominant. In more reductive conditions, arsenic concentration is decreased together with reducing of iron(II) concentration, this prove that, the As(III) transfered to arsenide and precipitated with sulfide and another ions. The sulfate-reducing bacteria are very important to arsenic metabolism, but they are only well metabolized in neutral pH. In the real pyrite taling site, the pH commonly is quite low during the intensive weathering period so these bacteria mostly develope in the post-weasthering period, whe-re pH values increased near neutral. The study improved knowledge about environmental protection in ore mining tail with purpose of environmental pollution reduction.Keywords Arsenic mobilization, behaviour of arsenic, arsenic releasing f-rom pyrite.