Abstract: Based on the signal separating and reconstructing of the Multi Taper Method – Singular Value Decomposition (MTM-SVD) method, this study investigates the impacts of interannual SST forcing associated with the El Ni?o-Southern Oscillation (ENSO) on precipitation over the middle and lower reaches of the Yangtze River Basin (MLYR), as well as possible underlying mechanisms. Our results show the MLYR precipitation is associated with the tropical Pacific SST at two distinct time periods, i.e., the quasi-biennial (2.4-year) and quasi-quadrennial (3.7-year) periods, which is related to the CP-type and EP-type El Ni?o, respectively. These two types of El Ni?o trigger different atmospheric circulation responses in the East Asia, both positively impacting the interannual variability in the precipitation over the MLYR. On the quasi-biennial period, the mature phase of CP-type El Ni?o leads to an East Asian-Pacific atmospheric teleconnection. On the quasi-quadrennial period, the mature phase of EP-type El Ni?o results in a meridional dipole-like distribution of atmospheric activity centers over East Asia. Additionally, both types of El Ni?o events trigger the western North Pacific anomalous anticyclone (WNPAC) during their mature phases. These atmospheric circulation systems collectively enhance the moisture transport from the South China Sea to the MLYR, thereby increasing local precipitation. Furthermore, our case analyses show that there is a difference in the relative contribution of the quasi-biennial and quasi-quadrennial periods to the MLYR precipitation variations in 2002. In the spring of 2002, the quasi-quadrennial period contributes to the increase in precipitation over the MLYR, while the quasi-biennial period weakens it. The opposite situation appears in the autumn of 2002. This study refines our understanding of how the multi-timescale forcing of the tropical Pacific SST affects the interannual variability of MLYR precipitation. Our conclusion can help to improve the accuracy of local precipitation forecasts in the MLYR.