The multiscale variability in summer extreme persistent precipitation (SEPP) in China from 1961 to 2020 was investigated via three extreme precipitation indices: consecutive wet days (CWDs), total precipitation amount (TPA), and daily precipitation intensity (DPI). The relationships between precursory and concurrent global oceanic modes and SEPP were identified via a generalized linear model (GLM). The influence of oceanic modes on the SEPP was finally investigated via numerical simulations. The results revealed that the climatological SEPP (>14 days) mainly appears across Tibetan Plateau, Yunnan-Guizhou Plateau, and South China coast. The first EOF mode for all three indices showed strong signals over the Yangtze River. Further analysis via the GLM suggested that the positive phases of the TNA in autumn, ENSO in winter, the IOB in spring, and the WNP in summer emerged as the most effective precursory factors of SEPP, which could serve as preceding signals for future predictions, contributing 30.2%, 36.4%, 38.0%, and 55.6%, respectively, to the GLM. Sensitive experiments revealed that SST forcing in all four seasons contributes to SEPP over China, whereas the winter and summer SST warming over the Pacific and Indian Ocean (IO) contributes the most. The hydrological cycle diagnostic suggested that water vapor advection predominantly originates from the western Pacific and IO in summer, driven by the strengthened subtropical high and Asian summer monsoon (ASM). The enhanced vertical water vapor transport is attributed to stronger upward motion across all four seasons. These findings are helpful for better understanding SEPP variabilities and their prediction under SST warming.