利用 NCEP1°×1°再分析资料与地面降水资料，通过涡度、流场以及水汽通量诊断等方法分析了20150816T00/20150819T00时发生在川、渝等地的西南涡暴雨天气过程。结果表明：蒙古西部低槽的东移发展与西太平洋副热带高压西伸为低涡暴雨的发生提供了有利的背景条件；初生于四川南部的西南涡缓慢东移至四川东北部地区，其东移过程中高低空涡度合并增强以及低层充足的水汽通量输送是造成此次暴雨过程的关键因素。“,”By use of NCEP1°×1°data for reanalysis and data for floor precipitation,an analysis is made of the rainstorm process that took place in Sichuan and Chongqing between August 16 and 19,2015.The results showed that the eastward movement of the conditioning tank in west Mongolia and the westward extension of the subtropical anti-cyclone of the western Pacific Ocean offer a favorable background condition for the formation of a low rainstorm vortex;the slow eastward approach of the southwest vortex,which originally formed in the south of Sichuan,to the northeast of the province,reinforced in the process of mergence between the high and low altitude vortex and the sufficient water-vapor transfer in the bottom layer are the key elements to bring about the rainstorm.