近年来，南宁城市化进程明显加快，但同时强降水也呈现出频发、极端性增强的态势，为此，本研究利用耦合城市冠层模型的数值模式WRF-UCM，使用ERA5再分析数据并通过敏感性试验对2022年5月南宁市一次低涡型强降水过程进行了模拟。结果表明：（1）更新了土地利用信息并耦合城市冠层模型后，6 h累计降雨量的模拟结果在时空分布上与观测结果一致，并且更准确地反映出主城区的降水强度演变；（2）在丘陵盆地地形背景下，南宁城市土地扩张导致的“绕流”作用和热岛效应增强是引起降水变化的主要因素，其造成主城区至下风区 20 km 处的强降水出现时间提前 1~2 h、降水量增加 10%~30%，南部郊区及上风区降水减少约15%；（3）降水过程发展阶段，城市土地扩张引起的城区潜热通量和对流有效位能（CAPE）减少会抑制深对流降水发展，但是城区感热和地表土壤热通量增加造成的热岛效应，以及城市地表摩擦和“绕流”作用对近地层气流辐合及抬升运动的增强，更多促进了低涡前部的云雨水含量增加和对流云团新生发展，造成城区及下风区的强降水出现时间提前；降水过程中后期，低涡中心靠近引起的气流增强使得“绕流”作用影响表现更明显，同时降水增强导致的地表水汽再蒸发作用和925~700 hPa凝结潜热加热增加对低涡增强的正反馈作用，共同驱动暖云降水过程发展，造成降水效率提高，而城市局地环流发展又促进了对流云中冰相粒子与雨水的相互转化，导致对流云团强度的维持，从而延长了强降水的持续时间，造成累计雨量增加。

In recent years，the urbanization process of Nanning has accelerated significantly，but at the same time，heavy precipitation has also shown a trend of frequent occurrence and increased extremity. To this end，this study used the Weather Research and Forecasting system coupled with Urban Canopy Model（WRF-UCM），the ERA5 reanalysis data，and sensitivity test to simulate the heavy precipitation process of a low vortex type in Nanning in May 2022. Results show that：（1）After updating the land use information and coupling the urban canopy model，the simulation results of 6-hour cumulative rainfall are consistent with the observed results in the spatiotemporal distribution，and more accurately reflect the evolution of precipitation intensity in the main urban area； （2）Under the background of hilly basin topography，the circumfluence effect and the intensification of the heat island effect，both resulting from changes in surface characteristics driven by Nanning's urban land expansion， are the main factors contributing to precipitation changes，which causes the occurrence time of heavy precipitation to increase by 1~2 hours and the precipitation increase by 10%~30% from the main urban area to the down‐ wind area 20km，and the precipitation in the southern suburbs and upwind area decreases by about 15%；（3）In the development stage of precipitation process，the decrease of latent heat flux and convective effective potential energy（CAPE）caused by urban land expansion will inhibit the development of deep convective precipitation， but the urban heat island effect caused by the increase of sensible heat and surface soil heat flux in urban areas， as well as the enhancement of urban surface friction and circumfluence on the convergence and uplift of near-sur‐ face airflow，promote the increase of cloud and rainfall content and the new development of convective clouds in the front of the low vortex，resulting in the early occurrence of heavy precipitation in urban areas and downwind areas. In the later stage of the precipitation process，the enhanced airflow caused by the proximity of the center of the low vortex makes the effect of circumfluence more obvious，and the re-evaporation of surface water vapor caused by the enhancement of precipitation and the increase of latent heat of condensation at 925~700 hPa have a positive feedback effect on the enhancement of the low vortex，which jointly drives the development of warm cloud precipitation process and improves the precipitation efficiency，and the development of local circulation in the city promotes the mutual transformation of ice particles and rainwater in convective clouds，resulting in the maintenance of convective cloud intensity. As a result，the duration of heavy precipitation is prolonged，resulting in an increase in accumulated rainfall.