Many studies focus on the oxidation of arsenopyrite which results in the formation of acid mine drainage (AMD) rich of As

but effects of pH and Fe

2+

 on arsenopyrite bio-oxidation are rarely available. A strain of Acidithiobacillus ferrooxidans (A.f.) isolated from the AMD of Dabaoshan and a mineral arsenopyrite were used to study the biooxidation of arsenopyrite. Experiments were designed to compare the difference between abiotic oxidation and biooxidation of arsenopyrite in pH2.00

3.00 and 3.50 with or without additional Fe

2+

conditions in a period of 30 days. The concentrations of As ion

Fe

2+

 and pH values during the experiments were determined The results showed  the lower original pH value the higher concentration of As ion in the result solution of biooxidation without additional Fe

2+

. The concentration of As ion in the result solution of the original pH2.00 is about 15 times of that in the original pH3.50. A lower pH value can accelerate the biooxidation of arsenopyrite. The additional Fe

2+

can keep the pH value of bio-oxidation solution in a condition of lower than 4.00

which promotes the biooxidation of the arsenopyrite and concentration of As ion in the result solution. The results indicate that adding some alkaline substances in the acid mine drainage to increase its pH value can reduce its Fe

2+

concentration，decrease the bio-oxidation rate of arsenopyrite and reduce the concentration of As ions.