Abstract: On 7 July 2023, a large-scale heavy precipitation event takes place in northwestern Liaoning, influenced by the Northeast cold vortex. An extreme hourly precipitation of 95.9 mm is recorded from 1800 BT to 1900 BT at Fangshan, Heishan County. A multi-scale analysis of this hourly extreme precipitation event is conducted using ERA5 reanalysis data, upper-air observations, automatic weather station observations, FY-4A satellite data, 3-dimensional mosaic products of weather radar base data (V3.0) and dual polarization radar data. The analysis focuses on large-scale environmental characteristics of this extreme hourly precipitation event, the development and evolution of mesoscale convective systems, and evolution characteristics of dual-polarization radar parameters during the event. These approaches reveal the role of the surface cold pool in the initiation and development of mesoscale convective systems that produced the heavy precipitation, as well as the relationship between 3-dimensional vertical structure and microphysical characteristics of convective systems and the extreme precipitation. Results indicate that during this process, an occluded front exists near the Northeast cold vortex. The heavy precipitation area is located near the occluded front system, within the southeast quadrant of the mature cold vortex. Fangshan, where extreme hourly rainfall occurs, is situated close to the warm front of the occluded front system. At the same time, there is a continuously strengthening southwest low-level jet in the lower layers, which transports warm and moist water vapor to the heavy precipitation area, providing favorable dynamic and moisture conditions for this hourly extreme precipitation event. Under combined effects of cold pool outflow generated by evaporative cooling of surface precipitation, the topography of the Yiwulü Mountains, as well as warm and moist environmental airflow, convective cells are continuously triggered in areas with high temperature gradient. The train effect formed by continuously emerging cells is the core cause for this hourly extreme precipitation event. The heavy rainfall belt shows a southwest-northeast distribution, closely aligns with the terrain, and continuously passes through Fangshan, causing an extreme hourly precipitation of 95.9 mm and accumulated rainfall of 190.3 mm in 5 h. During the extreme hourly precipitation period, there are two main convective storms affecting Fangshan, resulting in two precipitation peaks. Both strong convective storms are characterized by high values of reflectivity (Z), differential reflectivity (Z_DR), and specific differential phase (K_DP) values, accompanied by Z_DR and K_DP columns developing above -20 ℃ level, indicating abundant ice-phase particles. However, there are also differences, the first precipitation peak is mainly due to raindrop coalescence and growth, featuring large diameters and low concentrations; the second precipitation peak had high raindrop concentration, smaller drop diameters, and is accompanied by incompletely melted ice-phase particles.