East Asian summer monsoon (EASM) is one of the most dominant climate systems in East Asia. The anomalous EASM can cause extreme high temperatures, floods or drought. And the El Niño-Southern Oscillation (ENSO), the dominating mode in the tropical Pacific, is the most important factor affecting EASM. Understanding the processes for interannual to interdecadal variability of EASM-ENSO relationship is crucial.