Abstract: To reveal the causes of local rainstorm, and provide references for forecasting and early warning of agricultural disastrous weather, based on conventional observation data, encryption automatic station data and doppler radar echo data, the authors diagnosed and analyzed circulation background, physical quantity field and meso scale system of a rainstorm process from July 4 to 5, 2012 in northwestern Shandong. The results showed that: the main system of the rainstorm was the westerly trough, shear line and the low-level jet; the development of strong water vapor convergence time revealed by water vapor flux divergence in Liaocheng did not had a good relationship with enhanced vertical movement time, so the strong precipitation time was short; the spatial correlation between the precipitation area and the strong upward motion was better; the release of unstable energy triggered by convergence line in the lower troposphere produced rainstorm; the local characteristics of the rainstorm process could be explained by using small and medium scale system, the tracking of small and medium scale system was dependent on the development and application of the regional station data; the strong radar echo monomer and gust front of doppler radar could well explain the local rainstorm process, and the application of doppler radar products should be further studied.