Abstract: The markerfree technology has been an important content of safetransgenic research. On one hand, removal of selective marker genes could help to eliminate the publics fear of transgenic; on the other hand it would help scientists to multitransformate the foreign genes into the transgenic plants. This review summarized several methods of removing correlative marker genes and gave a prospect of their development．

Key words: transgenic plant, markerfree, conversion system, sitespecific recombination