Based on the data of weather modification and hailfall at Zhangjiajie in the north-west area of Hunan Province in the summer of 2005,the radar echo characteristics of hail cloud are analyzed,and the results show that a small mobile radar can have more RHI pro-files to supply a deficiency far from Doppler radar in hail-preventing activity,One qualitative and four quantitative identification indexes for the hail cloud identification are found,and with the indexes the hail cloud may be rapidly and accurately distinguished.