By use of the daily data of severe local storm in Beijing area and Beijing’s sounding from April to September of 1980￣1988

the favourable conditions for the storm genesis are identified. They are (1) low pressure in the lower troposphere

(2) unstable stratification in the troposphere and POtential instability in the middle-low troposphere

(3) high vapour content in the lower troposprere and large relative humidity in a deep tropospheric layer. The storm genesis is independent of strong wind in high tropsphere

vertical wind speed shear and dryness in the middle troposphere.