Abstract: This study analyzes the relationship between lightning activities and cloud microphysics within two isolated thunderstorm cells that occurred over southern China on 13 and 20 June 2016, respectively. Possible physical processes that affected the lightning activities are explored. The observations used in this study include data from S-band polarimetric radar, lightning-detection system and soundings. The results are as follows: (1) There is a lag relationship between lightning activities and changes in horizontal reflectivity (Z_H) intensity and supercooled liquid water content in the mixed-phase region. It can be used for early warning of lightning activity. (2) Prior to lightning activities, an increase in positive differential reflectivity (Z_DR) facilitates lightning activities, particularly when large Z_DR values are present in the mixed-phase region. However, this relationship is weak during the second stage of lightning activities. (3) The variation of graupel content suggests that riming electrification dominates the electrical process during early lightning activities; however, the leading role diminishes as lighting activities progress. This study is expected to deepen our understanding of cloud microphysics related to lightning activities within isolated thunderstorms.