Abstract: The purpose of this paper is to investigate the system of "circulation pattern-weather-corn yield" for the southern region of China. A long-term fluctuation of 20-30-yr period and a short-term fluctuation of 2-3-yr period for the system are discovered. The characters of the quasi-periodic fluctuations of the large-scale circulation systems are explicated. The model of long-term fluctuation for "Circulation pattern-weather-corn yield" for the southern region of China can be summarised as that when Australia high pressure and Pacific equatorial depression belt are weaker in spring,the Northern Pacific] anticyclone will be stronger in summer,so that there will be a wet period and a low weather yield period for rics there.In reverse,tthere will be a dry period and a high weather yield period for rice there.