The invention discloses a comprehensive utilization method for arsenic and acid wastewater, Arsenic and acid wastewater generated by nonferrous metallurgy and sulfuric acid industries is used as a process object, prereduction, evaporation and concentration are conducted, after concentrated liquid is cooled, trivalent arsenic is crystallized in the form of arsenic trioxide, through filtration separation and drying, arsenic trioxide is obtained, the evaporating liquid is condensed and reused, filtered concentrated acid and arsenic-containing soot are mixed for briquetting, sulfatizing roasting is conducted, arsenic trioxide in soot is recovered and used as a crude white product or further reduced for preparing metal arsenic with the crystallized arsenic trioxide, generated roasting sand is subjected to wet leaching, and valuable metal is extracted. Waste acid does not need to be neutralized, arsenic-containing waste slag is not generated, waste is controlled through waste, comprehensiverecycling of all elements of valuable components is achieved, meanwhile, the process is short, operation is simple, the treatment cost is low, the economic benefits are considerable, and the problem of acid wastewater treatment in the industry can be solved.