Based on the sounding data of Qingyuan Station from May to October from 2004 to 2009,11 kinds of vertical temperature differences are studied. The correlations between temperature differences and severe convective events are calculated and three kinds with higher correlations are further studied. The occurrence frequencies of severe convective events with different temperature differences are analyzed. The results show that temperature differences in severe convection days at lower altitudes in different months are small, compared with distinct amplitude at high altitudes. The frequencies of severe convective events increased with the increasing of temperature differences at both low and high altitudes. Severe convective events mainly occurred when the temperature difference between 850 hPa and 500 hPa was no less than 20 ℃, and that between 850 hPa and 700 hPa was no less than 6 ℃. When temperature difference between 400 hPa and 100 hPa was between 64 ℃ and 66 ℃ and that between 850 hPa and 500 hPa was between 23 and 26 ℃ or temperature difference between 850 hPa and 700 hPa was between 8 ℃ and 11 ℃, the frequeny would be the highest. As for large scale convective events when temperature difference between 850 hPa and 500 hPa was equal or greater than 24 ℃ or temperature difference between 850 hPa and 700 hPa reached 10 ℃，usually there was gale accompanied with heavy precipitation. When temperature difference between 400 hPa and 100 hPa was less than 60 ℃, the probability of large scale heavy precipitation would be very little.