Abstract: Based on the data of SST and NCEP/NCAR reanalysis data, the relationship is analyzed of springSSTA in the Kuroshio region with summer precipitation in China, summer 500 hPa field and water vaportransport, using the methods of Morlet wave, correlation and composite analysis. The results show that annualand interdecadal change of spring SST in the Kuroshio region is distinct. Spring SST displays a significantlyincreasing trend and there exist different periodic oscillations in the Kuroshio region, with the 23-yearperiodic oscillation being the most obvious. Troughs and ridges in the mid- and higher- latitudes turn deeperin high Kuroshio SSTA years. At the same time, the Western Pacific subtropical high strengthens andstretches westwards. As a result, the warm/wet air from the west of the subtropical high locates in the midandlower- reaches of the Yangtze River and south China and summer rainfall in the above regions increasesaccordingly. Composite anomalous water vapor flux fields indicate that the vapor transport from the SouthChina Sea and western Pacific and the vapor from the north converge over the mid- and lower- reaches of theYangtze River and south China, which results in the increase of the summer rainfall in the mid- and lowerreachesof the Yangtze River and south China. On the contrary, the summer rainfall in the mid- and lowerreachesof the Yangtze River and south China decreases correspondently in low Kuroshio SSTA years.