It is found that the relationship between the phase of 50 hPa QBO in summer season and the precipitation and drought/flood trend in the south of North China is featured with distictive stages, and is notably affected by the 11-year solar cycle. For the period of 1951-1989, in the even-numbered 11-year solar cycle the positive anomaly occurs in the west phase of the 50 hPa QBO and negative anomaly occurs in the east phase of the QBO, while in the odd-numbered 11-year solar cycle the positive anomaly occurs in the east phase of the 50hPa QBO and negative anomaly occurs in the west phase of QBO. The evolution of QBO intensity at 59 hPa is analyzed, which shows the marked sudden change processes, andin the odd-numbered 11-year solar cycle the intensity of east zonal wind is stronger than that in the even-numbered cycles.