Method for treating arsenic polluted soil

The invention discloses a method for treating arsenic polluted soil. The method includes the steps: mixing the polluted soil and NaOH into a semi-solid system and oxidizing low-valence arsenic in the soil under an alkaline condition in the semi-solid system; adding ferric salt into the oxidized polluted soil for stirring reaction; and combining the ferric salt with the pentavalent arsenic to generate stable compound ferric arsenate. By the aid of the method, the arsenic polluted soil can be treated without completely leaching the arsenic, a leaching toxicity test is made for the treated soil, and the arsenic content of leachate is lower than 1mg/L and meets the national standard.