Abstract: The Northeast Cold Vortex (NECV) is a key circulation system driving warm-season precipitation patterns in northern China, frequently triggering local heavy rainfall and severe convection. To better understand the fine-scale structure of precipitation within NECV systems, investigating the spatiotemporal distribution characteristics of warm-season NECV precipitation is of great scientific significance and provides valuable reference for forecasting. Using hourly ERA5 reanalysis and Global multi-source Merging-and-Calibration Precipitation dataset for the warm seasons (April–September) from 2001 to 2019, this study focuses on the mature stage of NECVs. A dynamic, center-referenced relative coordinate composite method is employed to analyze the spatiotemporal distribution and environmental configurations of NECV precipitation under different intensities and scales. The results show that warm-season NECV precipitation exhibits pronounced asymmetry in the relative coordinate system. Statistical results indicate that strong NECVs are more likely to form compact, near-center rainbands, whereas weak NECVs tend to produce loose, peripheral patterns, and large-scale NECVs generally correspond to broader rainbands and stronger core intensity. Diurnally, NECV precipitation in Northeast China generally follows a “secondary morning peak, primary afternoon peak” pattern. Strong NECVs maintain this bimodal structure, while weak and small-scale NECVs shift toward a single afternoon peak associated with thermal convection. Persistent heavy rainfall (PHR) events under NECV background exhibit an asymmetric “weak inner core, strong periphery” distribution. They occur most frequently in the southeast quadrant, while the southwest quadrant shows the strongest event intensity. Furthermore, these events are predominantly short-duration processes, with extreme cases (≥5 h) occurring only in the southern sectors of the vortex. Overall, different intensities and scales of NECVs correspond to distinct precipitation distribution characteristics, indicating a close relationship between the intrinsic properties of the vortex and the spatial structure of precipitation. From the perspective of a relative coordinate system, these findings refine the spatial differentiation characteristics of precipitation and PHR events during the mature stage of NECVs, providing a scientific basis for identifying high-risk precipitation areas and improving fine-scale forecasts under NECV conditions.