Arsenic(Ⅲ) is toxic and rather difficult to be purified from water. Natural pyrite has a lower capability to remove arsenic(Ⅲ) from solution than pyrrhotite. However, when heated in nitrogen gas, most pyrite generates pyrrhotite, which is a kind of porous material which has high surface area and stronger chemical activity and is very useful for arsenic(Ⅲ) removal from groundwater. In this paper, the authors investigated the influence of heating temperature, heating time, pH and dissolved oxygen on the removal of arsenic(Ⅲ) by heat-treated pyrite. The results show that monoclinic pyrrhotite has the best removal efficiency for arsenic(Ⅲ), and hence temperature of 600℃ and time of 1 hour seem to be the best calcinations condition for arsenic(Ⅲ) by heat-treated pyrite. Moreover, an optimum pH in the range between pH 4 and pH 10 was observed for arsenic(Ⅲ) removal from aerobic aqueous solution, while a range between pH 7 and pH 10 was observed from anaerobic aqueous solution. Contrast to anoxic environment, the sorption efficiency and sorption rate of arsenic(Ⅲ) on heat-treated pyrite is much better from aerobic aqueous solution.