The Chinese new generation of Doppler weather radar (CINRAD) has the advantages of high spatio-temporal resolution. It can observe the change process of precipitation intensity and the real-time movement of precipitation area in detail, and also can effectively monitor disastrous weather events. In this paper, the spatio-temporal distribution characteristics of summer precipitation in South China are investigated based on Doppler multiradar mosaic data in South China from 2017 to 2020. The results show that the frequency of summer precipitation in South China is dominated by stratiform precipitation. In most parts of South China, the frequency of stratiform precipitation is more than 85%, while the frequency of convective precipitation only accounts for about 14%. The peak reflectivity and the frequency of convective precipitation in Guangdong are higher than those in Guangxi and Hainan. Both the peak reflectivity and precipitation frequency show strong diurnal variation with local solar radiation, and also exhibits discernible regional differences. The reflectivity peak is roughly similar to the spatial distribution of convective precipitation, and the frequencies along the coast are higher than those in the inland region. Stratiform precipitation occurs most frequently in the inland region than along the coast. The frequency of stratiform precipitation is mostly concentrated at night with peaks seen in the morning. The peak reflectivity and convective precipitation are mostly concentrated in the daytime, the high-value region expands from the western coast to the inland and eastern coast as time changes, reaching the peak between afternoon and night. The diurnal variation of convective precipitation exhibits different bimodal patterns in coastal and inland region. A major peak appears in the morning and a secondary peak in the late afternoon, and the morning peak in central Guangdong is significantly lower than the afternoon peak.