The purification of crude arsenic by vacuum sublimation is theoretically analyzed in terms of thermodynamics and separation coefficient,and the vacuum sublimation process experiments and trial production are carried out.A large amount of tests and exploration show that when the crude arsenic is treated by vacuum sublimation for one time,the impurity elements of antimony,bismuth and selenium are to difficult remove,and among them,the antimony impurity element has the highest content;when the crude arsenic is treated by vacuum sublimation under lower tempera-ture,the removal of antimony is effective with removal rate reaching 82.7 % at most.