The satellite-based TRMM rainfall and the JRA55 atmospheric reanalysis datasets are used to investigate the structure and evolution of extratropical atmospheric intraseasonal oscillation and its impact on anomalous rainfall over South China (SC) in the summer (May to August) of 2002. Wavelet and power spectra analyses demonstrate that the intraseasonal variability of the SC rainfall during the summer of 2002 was characterized by a significant quasi-biweekly oscillation (QBWO) with a period of 10-30 days. Composite analyses show that such a QBWO of the SC rainfall was not only related to alternate occurrences of the anticyclone and cyclone anomalies in the lower troposphere over the coastal region of SC that modulate the western North Pacific subtropical high entering or leaving the South China Sea, but also largely dependent on the extratropical atmospheric oscillation in the middle and upper troposphere. The QBWO in the upper troposphere was characterized by a southeastward-propagating wave train consisting of a series of anomalous cyclones and anticyclones, which were aligned in a northwest-southeast direction over Eurasian continent. When the anomalous anticyclone and cyclone were respectively located over the Tibetan Plateau and northern China as the wave train moved, the upper tropospheric divergence between this dipole in anomalies was favorable for the development of ascending motions over SC, leading to above-normal rainfall; in the opposite situation, below-normal rainfall occurred over SC. For the transition between dry and wet episodes of the QBWO, anomalous tropospheric horizontal temperature advection and absolute vorticity anomalies in the upper troposphere above the subtropics caused by the southward migration of the wave train are two dominant factors leading to the alternation between ascending and descending motions over SC as well as the reversal of the corresponding meridional circulations. Local sensible heating anomalies also make certain contributions to the above process. Significantly positive correlations were found when the 500-hPa geopotential height anomalies over the Tibetan Plateau led the SC rainfall anomalies by 4 days (that is, a phase lag of 1/4 period of the QBWO), which implies that the 500-hPa geopotential height anomalies around the Tibetan Plateau may be a potential predictor for the forecast of the intraseasonal variation of rainfall over SC.