Abstract:Based on the observation and reanalysis data, the spatial mode and corresponding circulation characteristics of precipitation anomaly under pentad scale in Southern China during the 2015 flood season (from April to September) are analyzed by using the methods of empirical orthogonal function (EOF), composite analysis and significance test. The results show that the west east reverse pattern of precipitation anomaly is the major mode in the developing phases of strong El Ni〖AKn~D〗o years and the pentad pattern in 2015 shows similar features. But the pentad scale of precipitation anomaly patterns can be divided into two types of west east reverse patterns by using the first and third EOF mode, and they have obvious differences in upper, middle, lower levels of the troposphere. The precipitation anomaly pattern of more in east and less in west (A1) with the first EOF mode is dominated by the anticyclone activities around Philippines at the low level, but the pattern of more in east and less in west (A2) with the third EOF mode is dominated by tropical cyclone activities. The pattern of less in east and more in west (B1) with the first EOF mode is obviously affected by the moving southward of the cold air activities, but the pattern of less in east and more in west (B2) with the third EOF mode is dominated by abnormal position of the anticyclone activities around Philippines at the low level. The precipitation anomaly features of west east reverse pattern in Southern China during the 2015 flood season are closely related to the positions of anticyclones around Philippines, tropical cyclone activities and the moving path of the cold air activities.