The climatic jump of the western Pacific warm pool and its climatic effects were analyzed using the SST (COADS, NCEP) datasets. The results show that the warm pool has significant interdecadal variability with periods of 10 to 20 years and four major climatic jumps with periods of 40 to 50 years for a time dating back for more than 100 years, which happened in the 1910s, 1930s, 1950s and 1980抯. The warm pool jumps have important climatic effects. After the jumps,the SST increases by about 0.5C in central and eastern tropical Pacific; the Pacific subtropical high at 500 hPa strengthens and goes southwestward, the precipitation bands tend to be in southern China. The results also show that El Ni駉 event will happen more often than the La Ni馻 event when the warm pool anomalously develops, and the La Ni馻 event will happen more often than the El Ni駉 event when the warm pool anomalously declines. Over the recent 40-to-50 year period,the warm pool is still in its strengthening stage and it is possible that the drought in northern China will continue in the first decade of 21st century. The climatic jump of the western Pacific warm pool and its climatic effects were analyzed using the SST (COADS, NCEP) datasets. The results show that the warm pool has significant interdecadal variability with periods of 10 to 20 years and four major climatic jumps with periods of 40 to 50 years for a time dating back for more than 100 years, which happened in the 1910s, 1930s, 1950s and 1980’s. The warm pool jumps have important climatic effects. After the jumps, the SST increases by about 0.5C in the Pacific subtropical high at 500 hPa strengthens and goes southwestward, the precipitation bands tend to be in southern China. The results also show that El Ni 駉 event will happen more often than the La Ni 馻 event when the warm pool anomalously develops, and the La Ni 馻 event will happen more often than the El Ni 駉 event when the warm pool anomalously declines. Over the recent 40-to-50 year period, the warm pool is still in its strengthening stage and it is possible that the drought in northern China will continue in the first decade of 21st century.