Trans?translation is a key component of translation quality control system in bacteria， it almost exist in all bacteria. It consists of transfer messenger mRNA （tmRNA） and its chaperone protein small protein B （SmpB）， which can rescue ribosomes that are trapped due to the translation of non?stop mRNA. In addition， trans?translation also regulates the expression of specific genes and is involved in certain stress responses of bacteria. In this review， we collected the latest research progress in trans?translation， explained the structural basis of tmRNA and SmpB in trans?translation， demonstrated the specific mechanism of trans?translation in the recognition and rescue of stalled ribosomes， and summarized the function of trans?translation and its application， which was expected to provide reference for related research.