By use of monthly precipitation at 160 stations over China, ERA-40 reanalysis data and NOAA ERSST extend-reconstructed global sea surface temperature data, the authors find that the precipitation pattern over eastern China experiences two interdecadal variation processes in recent 50 years, and has close relation to interdecadal variation of the North Pacific SST. In the interdecadal variation process of the mid- and late-1970s, the precipitation pattern form north to south over eastern China changes from “＋－＋” to “－＋－” tripole distributions, and has close relation to the PDO (Pacific decadal oscillation) phase, with SST anomaly from positive to negative in the mid-latitude area of the North Pacific. East Asian summer monsoon circulation is a main bridge of PDO influencing the precipitation pattern. In the interdecadal variation process of the late 1980s and early 1990s, the precipitation pattern changes from “－＋－” tripole to “－＋” dipole distributions, and has close relation to higher SST from the northwestern Pacific to the south of Japan and round the Philippines. The first interdecadal variation shows that the same mode changes from one phase to another, and the second one exhibits the changes between different modes.