Abstract: Nitrile hydratase (NHase) is the biocatalyst which has been used in industrial bioconversion of acrylonitrile to acrylamide using microorganisms.Recent advances in the studies on structure,mechanism,photoreactivity,thermostability,etc.about NHases are reviewed.NHases contain metallic ions,which act as accessory factors in the active sites.The metal-binding sites play a crucial role in the enzymatic reaction.The photoactivation mechanism of Fe-type NHases is clarified.An endogenous NO is bound to the non-heme iron in the inactive NHase and its photodissociation activates the enzyme.From a practical point of view, the Nhases previously reported are still unsatisfactory catalysts because of their relatively low thermostability and the availability of some thermostable Nhases will help to reduce the inactivation of the enzyme.It is also clarified that amide compounds are essential for subunit assembly to yield active NHases.Some other factors are also discussed in this paper.Some perspectives on future research of NHase are presented.