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The aridity index is calculated and the dryness/wetness characteristics are analyzed based on the daily meteorological data of 104 stations from 1961 to 2006 in the Huanghuaihai region. The Huanghuaihai region is divided into five dry/wet climatic types: wet, semiwet, semiwet and semidry, semidry and semiwet, and semidry regions. The “semidry” region has the largest area compared with the other regions. There is obvious latitudinal distribution in the five climatic regions. Differences of dry/wet characteristics among different seasons are analyzed and the results show that summer is the wettest while spring and winter are drier. Compared with the 1970s’ and 1990s’, the areas of “semidry” region in the 1960s’ and 1980s’ are relatively larger. The areas of “semiwet” and “semiwet and semidry” in the 1980s are the largest compared with those in the other time, which shows that the 1980s was a relative wet period in the Huaihe River valley. The analysis of annual aridity index variation in the Huanghuaihai region shows that there is an increase tendency in the difference between dry and wet regions; i.e., the dry region is becoming drier while the “semiwet and semidry” region, as well as “semiwet” region, is becoming wetter.