Lightning is an important natural source of wildfires and oxynitride,and hence significantly influences ecological systems and atmospheric chemistry.Here,we choose South Asia,an important region for glo-bal water reallocation and global climate changes,to examine lightning variations based on the longest existing lightning dataset from the OTD/LIS observations.We identify a clear increase in lightning density in the research region,increasing at a rate of 0.096 fl km-2 a-1 over the last two decades.Multiple linear regression analysis is adopted to identify the main influencing factors among ten potential thermody-namic or microphysical factors and the crucial areas contributing to the increases in lightning.The sur-face latent heat flux along the west coast of the Indian subcontinent is the largest contributor,explaining 52％of the lightning variance and contributing to a 0.025 fl km-2 a-1 increase.The sea surface tempera-ture in the Arabian Sea,the convective available potential energy(CAPE)over the northwestern Indian subcontinent,and the wind shear along the northwestern coast also make important contributions to the lightning increase,indicating that the thermodynamic effects overwhelm the microphysical effects on lightning activity over the South Asia region.