Abstract: It is essential to fully understand the spatiotemporal distribution characteristics of heavy rainfall and design a characteristic rainfall process that aligns with the local rainfall distribution. This approach can allow for the early prediction of flood risk under specific rainfall conditions, which is crucial for building a flood disaster defense system. This study analyzes the spatiotemporal distribution characteristics of rainfall in Tianjin based on historical rainfall data. Results indicate that the spatiotemporal variability of rainfall in Tianjin is related to the underlying surface topography and the moisture sources that trigger rainfall. The distribution characteristics are complex and diverse. The extracted heavy rainfall spatiotemporal distribution features are clear, with well-defined physical mechanisms, providing valuable insights and references for flood risk management.