The meso-β-scale systems of the continuous heavy rainfall in South China (the middle part of Guangdong Province) in June 2005 were investigated through diagnosis of radar, satellite, and surface observation data, as well as numerical simulation output. The conclusions are as follows: (1) Meso-β-scale systems are the direct maker of the continuous heavy rainfall in Guangdong Province in June 2005. At the initial stage, there are some meso-γ-scale systems, which distribute in line and gradually combine to meso-β-scale systems.(2) The numerical simulation of meso-β-scale cloud cluster P indicates that there is convergence in the lower layer and divergence in the upper layer, which is very favorable for the initiation and maintaining of the heavy rainfall. The center of meso-β-scale rain cluster corresponds to ascending movement, and there is compensatory descending movement to the north of rain cluster. The meso-β-scale system bringing heavy rainfall exists in the warmest area of the warm sector ahead of front.(3) The similarities and differences of wind field in warm sectors ahead of front in Guangdong Province and Guangxi Province during the same heavy rainfall process are discussed, respectively. The former belongs to the wind direction convergence and the latter is related to the wind speed convergence.(4) Surface observation data provide important information. The intersection of surface convergence line and quite strong contrast zone of temperature and humidity contributes to the initiation of meso-β-scale systems significantly.(5) Based on these, a conceptual model of mesoscale systems of heavy rainfall in the warm sector ahead of front in South China and related influences of terrain, wind, temperature, moisture at surface on the heavy rainfall has been proposed.