The invention discloses a treatment method for high-concentration arsenic waste water, and relates to the technical field of sewage treatment. The method comprises the following steps of: 1, carrying out pH neutralization adjustment, and executing solid-liquid separation after neutralization; 2, oxidizing sedimentation (I): treating the arsenic waste water with an alkaline coagulant, then, executing oxidization, and carrying out inclined plate settling to realize solid-liquid separation; 3, oxidizing sedimentation (II): adding lime or lime milk in the neutralized waste water, executing oxidization simultaneously, and carrying out inclined plate settling to realize solid-liquid separation; 4, ferric salt coagulation: adding an inorganic coagulant in water solution, stirring, and then, adding an organic flocculant; and 5, air floatation separation: adding a surface active agent, separating iron and arsenic slag, executing pressure filtration and drying, and carrying out oxidizing roasting. The method has the beneficial effect that the effluent As concentration of the treated waste water can meet the national emission standard; the As concentration of the leach liquor of the oxidized and roasted arsenic waste residue buried underground is far below the national stipulated limit, and arsenic is cured effectively.