Abstract: To study the organization mode and evolution characteristics of mesoscale convective systems (MCS) that cause heavy rain during rainstorm days in Taishan region as well as possible influence of terrain, the modes and evolution characteristics of MCS are analyzed using the new generation composite radar reflectivity data, satellite data and operational observation data from May to October during 2020—2022. The results show that MCSs in Taishan area can be divided into six classes: Nonline-MCS (NL), Embedded line MCS (EL₁), Embedded lines MCS (EL₂), Trailing stratiform MCS (TS), Training line MCS (TL) and Parallel stratiform MCS (PS). Four of them are the same as previously classified archetypes, and the EL₂ and TL are two new statistical classes in Taishan region. On satellite cloud charts, the six classes often appear as irregular ovals or long stripes with the highest black body temperature (TBB) below −50°C, making it difficult to distinguish detailed mode of MCS. However, the new generation of weather radar data can make up for this defect. According to the analysis, NL, EL₁ and EL₂ are the main classes affecting the Taishan region, accounting for 86% of the total samples, and EL₁ is the most common. EL₁ class, including the embedded line (EL) in existing research results and the convective line without stratiform rainfall (NS) , originates in the area from Xingtai to Dezhou and Liaocheng, and mostly moves along the southeastern direction. The second most common class is the NL, which generates in the Taishan area with strong echoes dispersed and little movement; the third is the EL₂ class, which generates in the area between Kaifeng and Hefei, and mostly moves along the northeastern direction after formation. Except for the EL₂ and PS, the other classes appear with a distinct diurnal variation,showing two peaks in the afternoon and at night respectively. Taishan has impacts on the intensity, shape, moving speed and direction of most rainfall echoes, especially on the formation of TS and the transformation of NL into EL₁ and EL₁ into EL₂ or NL. According to statistics, only 12% of MCS modes do not change significantly, and the rest of the samples change every 1.5—3 h. In contrast, NL is not only one of the main classes that cause heavy rain in Taishan area, but also an intermediate mode in the evolution of other MCS in many cases.