Abstract: The paper aims to accurately analyze and forecast rainstorm drop area in Guizhou. Based on FNL information NCEP 2.5°×2.5° and conventional numerical weather maps and other information, the cause and forecast deviation of a wide range of strong rainstorm process on June 13, 2015 in southern and southeastern Guizhou were analyzed. The results showed that: air vortex cooling tank, small south branch tank and the establishment of low-level jet acted as the directing impact system of the heavy rain process; the location of frontal zone of equivalent potential temperature had a certain indication on the time and location of the heavy rainfall, and lower negative vorticity and high positive vorticity over heavy rain area formed a suction structure, vorticity moving direction was more consistent with the moving direction of weather systems. Strengthening subtropical slow westward was the key blocking eastward shift of precipitation, the supplement of nearly formation north by northwest path of cold air provided trigger condition for torrential rain, while vertical speed played a good indication role in strong convective weather forecast. EC mode had good prediction time and magnitude of heavy rain in Guizhou, but there was a deviation for rain drop area.