Abstract: Based on conventional observation data, ERA5 reanalysis data and Yongzhou Doppler radar data, the heavy rainfall occurring in Southern Hunan Province from 12 to 13 August 2016, which was affected by easterly wave, was analyzed. The results show that the heavy rainfall process occurred in the period when the 200 hPa South Asian high was converting from the western type to the eastern type, and the central and eastern China were controlled by the Western Pacific subtropical high (WPSH). The mesoscale low vortex was induced by the southwest monsoon and easterly wave on the south side of WPSH, and it was the low vortex that increased the vertical wind shear and made the easterly wave maintaining for a long period of time. The main rainfall area was located in the zone where the mesoscale low vortex passed through. It was also within the range of the northeast wind in front of the easterly wave trough. Both the frontal zone of energy on the west side of the vortex and the large value region of θ_se (equivalent potential temperature) in front of the easterly wave indicate the occurrence of rainstorm in a certain area. The precipitation intensity will increase significantly when the center area of the positive vorticity advection in front of the easterly wave overlaps with the lowlevel θ_se large value area. There is high correlation between the rainstorm area and the special terrain of southern Hunan. The large angle between the alignment of mountain and the warm moist flow makes the precipitation increase significantly.