Abstract:Linear plasmid is a new focus of basic microbiology research in recent years. The replication of linear plasmid, compared to the circular plasmid, has its own distinct characteristics—5'end patching mechanism by which bacteria can fill the single-stranded gaps caused by the removal of RNA primers at 5'end of the strand. According to the terminal structure of linear plasmid, linear plasmids can be divided into two categories：one kind of terminal structure is covalently closed hairpin, the other one is the end capped with the terminal protein covalently. This review introduced the progress of study on the replication mechanism of linear plasmid and focused on the 5'end patching mechanism of the two kinds of linear plasmid terminal structures.