Itwas p roved a false p rediction that the heavy rain would occur in Shijiazhuang on July 18, 2007, though the temporal - spatial distribution of synop tic systems and physics factors all indicated a hint of the rainfall. In order to find the reasons, some factors were diagnosed by using the conventionalmaterial and numerical p rediction p roducts. Results are as follows: (1) It is the main cause for false forecast that Shijiazhuangwas on the intermediate region of two shear lines, which resulted in a lack of vertical condition (mid dle - low shear line) ; (2) The estimation effect of convection development over Shijiazhuang by using physical quantities from Xingtai station is notwell; (3) A lack of the effective numerical forecasting p roducts resulted in this false p rediction; (4) The rainstorm occurred in Xingtai and Handan should fall into southwest vortex rainstorm ; (5) The earlywarning ability of severe weather can be greatly imp roved using satellite cloud images, radar data and meteorological factors from national automatic station.