Zheng ''an county of Zunyi city suffered heavy rainstorm and flood disaster in 2020, and the hourly rainfall intensity broke through the historical extreme value since meteorological records began in our province. Synthetic aperture radar (SAR) images are used in this paper to identify the areas affected by heavy precipitation, classify the disaster risk, and explore the service of “three calls for response” in mountainous areas. This Research can take advantage of satellite remote sensing in disaster prevention and mitigation, and also provide reference for flood control and disaster relief and upstream and downstream joint prevention of river basins. The results show:(1) It’s necessary for flood control and dispatching in mountainous areas to pay attention to areas with heavy rainfall and consider the direction of rivers and the effect of precipitation overlap between upstream and downstream. Especially due to the enhancement of surface runoff confluence in areas with obvious elevation differences in front of high mountains, it is bound to strengthen the judgment linkage response. (2) The amount of rainfall is not necessarily proportional to the increase of surface water, so the flood control work cannot be judged solely on the basis of the amount of rainfall.(3)The results of this case have important supplementary significance to flood disaster prevention in Zheng ''an County, but it can only provide basic reference for the exploration of the relationship between prediction and response, the final establishment needs more statistical analysis of weather process cases.