Understanding the spatiotemporal characteristics of heavy precipitation and its potential impact on grain yield is crucial for determining better agricultural practices and adaptation to climate extremes. We conducted a case study in a major grain-producing region in China—Anhui Province—and studied the spatial patterns of heavy precipitation using 11 precipitation indices. We also assessed the relationship between the key heavy precipitation index and grain yield. The results showed that the frequency, continuity, and extreme value of heavy precipitation decreased gradually from the southern to northern regions of Anhui Province, whereas the precipitation concentration gradually increased from the central to northern and southwestern regions. The total precipitation of extreme rainy days (P95) was one of the most effective indices for detecting flood-affected agricultural areas. Based on different temporal variations of P95, the entire study region was divided into six sub-regions: south-central, north-central, southern, northwest, northeast, and northern. The climate-driven yield was the most sensitive to the interannual fluctuations in P95 in the north-central region. Furthermore, the area and intensity of the Asian polar vortex in summer may be important for P95 evolution in this region. The results of this study will help understand the changes and impacts of heavy precipitation in Anhui Province.