Based on monthly mean precipitation data from CRU,CMAP,PREC/L,CN05.1, NCEP/NCAR and 160 meteorological stations in China, the intraseasonal variation of the midsummer precipitation in South China and its related atmospheric circulations in recent 50 years were investigated by using the multi-variables statistic methods, including Empirical Orthogonal Function (EOF) decomposition, Season-Reliant EOF (SEOF), moving average, spatial correlation, regression analysis and composite analysis. Results show that the precipitation anomalies in both July and August exhibit consistent spatial variations. There are evident intraseasonal variations in midsummer precipitation over South China. During 1963-1993, there was an out-of-phase evolution of precipitation anomaly in July and August, which implys that more (less) rain in July almost corresponds to less (more) rain in August. However, there was an in-phase relationship in precipitation between July and August during 1994-2015, which presents more/less rainfall in August is generally accompanied by more/less precipitation in July. Further analysis suggests that the anomalous atmospheric teleconnection patterns play dominant roles in the two intraseasonal modes of the rainfall. For in-phase case, the anomalous circulation of the middle troposphere in July is mainly featured by typical Eurasian (EU) and East Asian/Pacific (EAP) teleconnection patterns, while it is related to the EU and Pacific/North American (PNA) teleconnection patterns in August. For out-of-phase case, the spatial pattern of circulation anomaly is similar to the North American East/West (NAEW) teleconnection pattern in July and the EAP teleconnection pattern in August. Meanwhile, the variation of the Western Pacific Subtropical High (WPSH) in July and August is closely related to the intraseasonal variation. In out-of-phase years, the east-west position of the WPSH changes evidently from July to August, while no significant change has been detected for in-phase years.