On July 1, 2016, there was a strong Meiyu frontal rainstorm process that caused severe flooding in Anhui, mainly triggered by two mesoscale vortex activity, with a "train effect" at the center of the rainstorm in Tongcheng, and a "train belteffect" at the sub-center in Chaohu.In this article, based on conventional observations, ground-based encrypted automatic observations, Doppler weather radar and the European Center for Medium-range Weather Forecasts (ECMWF) ERA5 reanalysis data at 0.25°×0.25°, the development of convection at the two locations and its relationship with the mesoscale low vortex activity were analyzed. Results show that this rainstorm occurred in a double blocking type, with a cold vortex aloft and a subtropical high pressure steadily maintained in the background, and the activity of two mesoscale vortices triggered the heavy precipitation.Multiple strong convective short rain bands moved from west to east under the guidance of upper air currents and passed through Chaohu Lake in sequence, forming Chaohu "train band effect". New storms that were constantly triggered passed through Tongcheng in sequence along the southwest-northeast direction rain band, forming Tongcheng "train effect". The storms affecting Chaohu and Tongcheng all had a low center of mass structure, and precipitation increased significantly after the storms merged. Chaohu "train band effect" was located on the right side of the cold shear line in the southwest quadrant of mesoscale low vortex C1. The dynamic instability was obvious. The cold air from the rear of the existing low vortex invaded the warm and humid air from the south, triggering convective storms, and then moved from northwest to southeast, passing through Chaohu Lake in sequence, and the ultra-low-altitude jet stream in the south triggered convective storms and then passed through Chaohu Lake from southwest to northeast, causing heavy precipitation. Tongcheng "train effect" was in the southeast quadrant of mesoscale low vortex C2. The thermal instability was relatively strong, the low-level cold air was not obvious, the deep low-level jet stream interacted with the boundary layer cyclonic convergence, and the backward-propagating storm moved from southwest to northeast, passing through Tongcheng, causing extreme precipitation.