The decennial evolvement of abnormal rainfall in flood season over the Loess Plateau of China were studied using the rainfall data of the recent 40 years.Results showed that the range of abnormal rainfall decreased in flood season.The rainfall belt significantly shif ted to the south with 1.8 lat.degrees from 1960s to 1990s and 0.6 lat.degrees from 1960s to 1980s.Each of the first 3 models of rainfall had different change points and periods

but multiple periods and weak surges corresponded wit h rainy time

being contrary to the time of rain shortage.The region sensitive to abnormal rainfall flowed from nort heast to southwest.The west part of the Loess Plateau tended to be arid.