The invention relates to a method for preparing a nonmetallic material, in particular to a method for preparing high-purity arsenic, solving the problems of high production cost, low output, impossible realization of industrialization, and the like of the traditional preparation methods. The method comprises the following steps of: loading industrial arsenic into a crucible and carrying out primary sublimation and distillation in a vacuum furnace; then loading the arsenic into an oxidation furnace, and introducing oxygen into the oxidation furnace to generate arsenic oxide; loading the arsenic oxide into a crucible and carrying out secondary sublimation and distillation in the vacuum furnace; loading the arsenic oxide subjected to twice distillation into a tube furnace, introducing high-purity argon and hydrogen into the tube furnace for reducing to obtain crystallized arsenic; loading uncrystallized black arsenic and unreduced arsenic oxide into a quartz tube, putting into the vacuum furnace for separating, and reducing obtained arsenic oxide; and finally, loading separated black arsenic and all reduced crystallized arsenic into the tube furnace together, introducing high-purity argon and hydrogen into the tube furnace for carrying out hydrogen sublimation protection to obtain 6N high-purity arsenic. The method has the advantages of simple impurity removal process, low cost and high output, solves the problem of pollution, eliminates potential safety hazards and achieves the purposes of generating the high-purity arsenic without pollution.