Abstract: Based on the observation data of precipitation at the stations and the reanalysis data of MERRA-2, the intraseasonal oscillation of the summer rainfall over the Yangtze River Valley in the summer of 2014 were analyzed,and the related atmospheric circulation was studied from potential vorticity perspective. The analysis shows that the intraseasonal variablility of precipitation in the Yangtze River Valley in the summer of 2014 was regulated by the 10-20d quasi-biweekly oscillation. In the extreme wet phase, the South Asian High is in a saddle shape pattern, just due to the combined effects of the positive anomalous potential vortices propagating eastward along the mid-latitude waves in the upper troposphere and the positive anomalous potential vortices propagating southwest on the east side of the South Asian High, forming a high-altitude divergent circulation in the Yangtze River Valley; in the middle and lower troposphere, when the mid-latitude anomalous cyclones propagates southesast to the north of the Yangtze River Valley, the anomalous anticyclone in the western Pacific extends to the southeast coast of China, enhancing the low-level water vapor convergence of the Yangtze River Valley. Due to the co-evolution between the upper and lower troposphere, positive rainfall anomalies persisted over the Yangtze River Valley. Furthermore, the ascending cold air under the upper-tropospheric positive potential vortices anomaly in the north of the Yangtze River Valley forced the anomalous ascending motions over the Yangtze River Valley and the anomalous ascending motions over the South China Sea. Such a meridional vertical circulation was favorable for the persistence of anomalous rainfall in the Yangtze River Valley. The opposite situation is for the extreme dry phase.