Abstract: By use of observational data in Zhujiang River Delta and GuangZhou's sounding from March to May of 1976-1983,the environmental conditions of genesis of tornado are analysed and compared with that of nontornadic severe local storm. It is found that the favorable conditions for tornado genesis are low pressure and stability of stratification,strong winds in a deep layer of the tropephere and high temperatures and humidity in the low level,which are qualitatively similar to those for severe local storms and larger convergece of low pressure,instability in stratification,and horizontal momentum over deep tropospheric layers of them are primary conditions for the storms to further develop into tornadoes. The latter has no mechanism connection with wind shears in the vertical.