The domesticstudies of theory and application on the helicity since 1990′s are reviewed substantially and systematically.The helicity is classified as vertical helicity,horizontal helicity and perfect helicity,meanwhile,the vertical helicity is classified as local vertical helicity and integrated vertical helicity.The formulas of vertical,horizontal and perfect helicity are introduced and provided,in the mean time,the status of each kind of helicity application to synoptic diagnosis is induced completely.What is more,the present applied situation of the helicity is discussed and analyzed simply,along with a prospective study in this field at last.