By use of the NCEP/NCAR daily reanalysis sea level pressure data from 1948 to 2002 and monthly rainfall and air temperature of 160 stations in China,the spatial and temporal variations of the frequency and intensity of spring Northern Cyclones have been computed,and relationships between spring Northern Cyclones and the temperature and precipitation over China also analyzed.Results show that in spring Northern Cyclones have high frequencies and there are two distinct high value centers:one locates in the middle of Mongolia;the other in the north of northeast china.There are obvious interannual and interdecadal variations in spring Northern Cyclones frequencies and intensities.With the decadal climatic catastrophe in global scale,there was a abrupt change in both frequency and intensity in the mid-last of 1970s,i.e.the frequencies and intensities of Northern Cyclones decreased from 1980s to 1990s.The frequencies of spring Northern Cyclones mainly have important influence on rainfall and air temperature in the north of china.When the spring Northern Cyclones are active(inactive),the rainfall is less(more) in the most part of North china as well as the north of Sinkiang;and the temperature is higher(lower) in the north of Sinkiang,whereas the temperature is lower(higher) in part of Gansu,Ningxia,Shanxi and Neimeng.In spring,the frequency-descending and the intensity-weakening of Northern Cyclones from 1980s to 1990s are responsible for the reduction of frequencies of sandstorms in compansion to the 1970s.