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 AOD and CG lightning flashes in both regions are nonlinearly related, with AOD thresholds of about 0.5 and 0.3, respectively. When AOD is below the threshold, the CG lightning flashes in both regions increase with increasing AOD. When AOD exceeds the thresholds, the relationship between the CG lightning flashes and AOD is scattered in both regions. However, in Region 1, the number of CG lightning flashes still increases overall with increasing AOD. In contrast, in Region 2, the CG lightning flashes initially show no significant change and then decrease with increasing AOD. In Region 1, the relationship between lightning activity and aerosols is primarily determined by the relationship between lightning occurring at night and aerosols. In Region 2, the relationship is mainly determined by the relationship between lightning occurring in the afternoon and aerosols. Because the radiative suppression effect of aerosols is stronger during the day and weaker at night, this may lead to different relationships between lightning activity and aerosols under high aerosol conditions in Region 1 and Region 2.. Furthermore, the diurnal variation of CG lightning flashes in Regions 1 and 2 shows bimodal and unimodal forms, respectively, under various aerosol loading conditions. Under high aerosol loading conditions, the evening peak over Region 1 and the afternoon peak over Region 2 are delayed.