Abstract: This study investigated the relationship between lightning activity and aerosols in the Sichuan Basin (region 1) and Guangdong region (region 2) by analyzing 9-year (2010-2018) summer datasets of cloud-to-ground (CG) lightning and aerosol optical depth (AOD) data. The results indicate that there is a non-linear relationship between AOD and CG lightning flashes in regions 1 and 2, with thresholds of~0.5 and~0.3 for AOD, respectively. When AOD is below the threshold, the CG lightning flashes in both regions increases with the increase of AOD. When AOD exceeds the thresholds, the relationship between the CG lightning flashes and AOD becomes scattered in both regions. However, in Region 1, the CG lightning flashes still increases overall with the increase of AOD, while in Region 2, the CG lightning flashes initially shows no significant change and then decreases with the increase of AOD. The relationship between lightning activity and aerosols in regions 1 and 2 is determined by the relationship between lightning and aerosols that occur at night and in the afternoon, respectively. Combined with the radiation suppression effect of aerosols, it is stronger during the day and weaker at night, which may lead to different relationships between lightning activity and aerosols in the two regions under conditions with high aerosol content. In addition, the diurnal variation of CG lightning flashes in regions 1 and 2 shows bimodal and unimodal forms under various aerosol loading, respectively. Under condition with high aerosol loading, the peak in the evening of region 1 and the peak in the afternoon of region 2 appear later.