This study employs ERA5 reanalysis data, station precipitation data from the China Meteorological Administration, NOAA monthly average SST (sea surface temperature), and outgoing longwave radiation flux data from 1980 to 2020 to analyze the impact of zonal position of EASJ (East Asian subtropical jet) on summer precipitation in China, as well as its response to SST in the tropical central-eastern Pacific. The results indicate that in westward-shift years of the EASJ, upper-level convergence and lower-level divergence play an important role in YRV (Yangtze River valley). The eastward displacement and weakening of WPSH (western Pacific subtropical high) at 500 hPa suppress moisture transport to the YRV, leading to reduced precipitation. Meanwhile, upper-level divergence over the Hetao area promotes rising motion, accompanied by lower-level moisture convergence, increasing precipitation in the Hetao area. Meanwhile, in eastward-shift years of the EASJ, the WPSH strengthens and shifts westward. The convergence and divergence patterns in the upper and lower troposphere, along with moisture conditions and vertical motion in these two regions, exhibit reversed characteristics compared with those in westward-shift years of the EASJ. As a result, the precipitation anomalies of eastward-shift years of the EASJ display an opposite phase distribution compared with in westward-shift years of the EASJ. The EASJ’s zonal position is closely related to the summer SST in the tropical central-eastern Pacific. In this region, negative (positive) SST anomalies directly cool (warm) the atmosphere, suppressing (enhancing) local convective activity. These alterations modulate Walker circulation and lead to anomalous ascending (descending) motion in the tropical western Pacific. The vertical motion anomalies further affect East Asia’s mid-latitude region through meridional circulation, reducing (intensifying) convective activity near 30°N. Consequently, the meridional temperature gradient in the eastern part of the climatological jet region decreases (increases) due to diabatic heating, weakening (strengthening) the tropospheric westerlies and resulting in an anomalous westward (eastward) EASJ.