Abstract: There are many defects in the alternating use of 3% hydrogen peroxide and saline during and after root canal instrumentation here in most of hospital in China. Sodium hypochlorite（NaClO） is widely used abroad in endodontics because of its strong antimicrobial action and tissue solvent activity. However, NaClO is also a tissue irritant and a toxic agent, and rubber dam is not widely used in China which has deterred its use. This paper reviews the research process in aspects of NaClO used as root canal irrigation which could contribute to popularize its domestic clinical application.