Weather events show that severe convective activities usually appear in front of a.typhoon which frequently initiate severe thunderstorms and tornadoes. Analyses on the processes of tornadoes in front of typhoons taking place in Jiangsu Province from 1962 to 1984 show that a tornado is forming in certain position where is always along the right-front side in the direction of the typhoon movement , and associated with the typhoon intensity and other factors.In this paper we also analyse the genesis factors of the tornado in front of a typhoon by means of meso-scaieverticity equation, We oint pout that the. slopes( grad w ) in vorticityequation is one of the important conditions of the tornado cyclone's genesis in severe convective clouds in front of a typhoon.