Abstract: Patent Troll refers to not only a specific type of patentees in practice， but also the phenomenon of patentees exercising patents. Patent Troll may be suspected of “indulging in infringement”or “fraud and coercion” causing some enterpriseshuge economic losses and intensifying the tool orientation of the patent system， which has affected the healthy operation of the patent litigation system. However， Patent Troll has also explored a model of patent operation; therefore， it couldnbe opposed or supported absolutely. To deal with Patent Troll， the patent legal system should be improved in terms of the judgment standards of patentability and the legal liability of patenteesmisconduct.

Key words: Patent Troll, patent litigation, patent operation