Abstract: Polydora Complex, typically marine bottom deposit feeders, mostly inhabit in the coastal waters including intertidal zones, bays and estuaries. Some of Polydora Complex are main shellfish parasites which can bore into shells, and retard growth and development of the hosts. The shellfish heavily affected with Polydora Complex have high mortality. This paper reviews the researches on Polydora Complex from five aspects, including morphological taxonomy, molecular phylogeny, habitat type, reproduction and larval development. Research trends for Polydora Complex are also forecasted.