Abstract: 15 hail weather processes appearing in Yuxi region in central of Yunnan in summer of 2002,2003 are analyzed.The conclusion is that the weather backgrounds and circumfluence characters of hailing in Yuxi region in central of Yunnan in summer are classified as the types of the two high pressure,the circumfluence of low pressure and the partial east current with south of auxiliary high pressure.The temperature and logarithm pressure chart of physics character has latent instability.Average exponent of Kis 36 ℃ and exponent of SIis 0 ℃.The changes of the intension of echo,the altitude of echo,the level scale of echo quantity of containing water and velocity scene of the cloud of hail are researched particularly with 15 hail weather processes.It is concluded that it will emerge the process of hail in ground when the altitude of intension of 40 dBz exceeds 7 km,and the top altitude of echo exceeds 9.5 km,and the ratio of the level scale of 30 dBz echo body of the temperature layer up 0 ℃ to the one of the temperature layer below 0 ℃ is larger than0.6.With the coming of hail,the level scale ratio is increasing gradually,the top altitude of cyclone or convergence is higher than7 km(the-10 ℃ temperature layer)and,VILincreases gradually.