This study reveals the close correspondence between the interannual variability of the dominant East Asian summer rainfall pattern and the diabatic heating over the Tibetan Plateau in both spring and summer. The heating fluctuation over the Tibetan Plateau is associated with two wave-like circulation patterns, which bear the characteristics of forced Rossby wave emanating away from the deep heating. The wave-like pattern in turn affects the East Asian summer rainfall. Because of the persistent heating over the Tibetan Plateau from spring to summer and its possible effect on the surrounding areas, the heating index defined in this study can be used as a good predictor for the JJA heating and precipitation distributions. Evidences shown suggest that external conditions other than the SST anomaly must be considered to understand the interannual variability of the East Asian summer rainfall.