The influence of El Niño on the intra-seasonal variations of East Asian summer monsoon (EASM) and summer rainfall is studied based on pentad mean reanalysis data during 1979-2012. It is shown that, during the El Niño decaying summer, the western Pacific subtropical high (WPSH) tends to extend more southwestward with a stronger intensity. The anomaly enhances with the seasonal march, with a weaker anomaly in the early summer and the anomaly reaches its maximum in the late summer. Based on the feature that summer rainfall in East Asia tends to advance northward in a stepwise way, we divide the major rainy period into four periods, i.e., the pre-flooding period in southern China, the Meiyu period over Yangtze-Huaihe River basin, the rainy period in northern and northeastern China, and the post-flooding period in southern China, and analyze the intraseasonal variations of the EASM and summer rainfall. During the above four periods, there appears a consistent anomalous circulation pattern in the lower troposphere. There is an anomalous anticyclone in the southern flank of the WPSH and a cyclonic anomaly in the northern flank, respectively. As a result, the moisture transport from the tropics and the cold air from high latitudes both intensify due to the enhancement of the easterlies to the south and the northerlies to the north of the WPSH, leading to more rainfall over the major rainy region. It is important to note that this anomalous pattern tends to move northward with the EASM, resulting in more rainfall during the major flooding period and less rainfall in other periods over each individual region of East Asia.