The weather system,thermal and dynamical features of the continued hail shooting weather process over a large area in Shandong Province on 28-29 April 1997 were analyzed.It is shown that the continued hail shooting process is caused by a cold vortex.The cold front triggered off convective instability energy and a stronger convection produced.Hail shooting located in the area with convective instability,high energy tongue at the middle-low level,warm advection and convergence in low level and cold advection and divergence at the high level,and ascending motion.CAPE and stronger positive vorticity advection affected importantly the hail shooting.