Bio-absorption has an unparalleled advantage over other traditional methods in removing and recycling heavy metal ions from waste water. Consequently, it has a promising future. In this paper, the traditional methods and the bio-sorption method via which heavy metals are removed from waste water are compared to summarize the mechanism of bio-sorption, the types of bio-sorbent, the factors that can influence bio-sorption and the state of its application in waste water treatment .