Abstract: The Bayer red mud is alkaline residue from alumina production by Bayer method.It contains a lot of aluminum， iron，and other metal elements which were not leached.It pollutes the environment and wastes resources to deal with dam stockpiling.High efficient flocculant polymeric aluminum ferric chloride（PAFC） was prepared by two the stage acid leaching method with the modified Bayer red mud as raw materials.Flocculation experiment results of PAFC showed that the product had better flocculating effect.Compared with traditional craft the new technique which omitted the process of adding alkali to regulate the basicity，made full use of hydrochloric acid and saved the cost of producing the PAFC.This study of inorganic polymer flocculant PAFC preparation provided a new process to resolve the environmental pollution and resource waste caused by the Bayer red mud damming up.

Key words: modified Bayer red mud, two stage acid leaching, PAFC