With radar observations of echo intensity, along with the information on weather conditions and hazards, as well as radiosonde data,the paper discusses the relationship between the top height of radar echoes and the hail probability associated with severe convection in Jiangsu Province. The single-parameter formula incorporating with conditional probability of hail is used to identify hail cloud. The data of the angle between the moving direction of band and strip-trpe echoes and the direction of upper airbwind are statistical analysized