Abstract: Long QT syndrome (LQTS) is a familial abnormality of cardiac rhythm. To date, mutations in 12 different genes have been associated with LQTS. In China, LQT2 accounting for 54.5% of the LQTS is one of the most common forms of LQTS. Congenital LQTS type II (LQT2) is caused by mutations in the human ether-a-go-go-related gene (hERG). hERG encodes the pore-forming α-subunits of channels that conduct the rapid delayed rectifier K+ current (IKr). hERG mutations lead to a reduction in the rapid component of the delayed rectifier repolarizing current (IKr), which contributes to QT interval lengthening . This paper mainly reviewed the mechanism, genetic testing and miRNA relationship of hERG mutations.