Abstract: In order to further explore the mesoscale physical mechanism of short time rainstorm in Shandong, ande analyze the mesoscale information before strong convection comes, improve the accuracy of regional rainstorm forecast in Shandong. Using the conventional observed data, the FY-2E satellite TBB data and NCEP/NCAR 1°×1° for 6 h reanalysis data on 2011 July 2-3 Shandong rainstorm process had been diagnosed in synoptic and dynamic. The results showed that: the Shandong heavy rainstorm was caused by high altitude, cold ground cyclone and subtropical high pressure system; the maintaining subtropical high pressure, the appearance of the low level shear line in lower troposphere layer, the incursion of the cold air in middle and higher troposphere layer, strong instability energy as well as the abundant and deep water vapor and other weather conditions effective and reasonable, caused the heavy rainstorm; positive vertical helicity center had a good relationship with the change of the southwest vortex’s movement and intensity. Heavy rainstorm happened near the transition zone of MPV1 and weak negative zone on 850 hPa, and it combined the convective instability and baroclinic instability; there was an important guidance to research the MCC changing scope and intensity.