Based on the conventional weather data and the Doppler radar data，a strong convective weather process occurred on July 3，
2007 in Chengde of Hebei Province was analyzed． Results show that the change of atmospheric unstable index and the level and vertical
distribution of θse can reflect the atmospheric stratification condition and the unstable energy accumulation． The temperature advection
and the vertical distribution of helicity can demonstrate the atmospheric thermal and dynamic characteristics before the strong convection
weather occurrence． The divergence and vertical velocity changing with time and height triggered the strong convection weather． The
configuration of high and low level wind field and the air vent index can judge the size of vertical wind shear． The Doppler radar basic
reflection factor played a key role in the pre － alarm of a strong convection weather．