Using the NCEP/NCAR re-analytical dataset and summer precipitation data over North China,we define the Arctic Oscillation index according to the conception of Arctic oscillation proposed by Thompson and Wallace,and study the inter-decadal variation of Arctic oscillations and its relation with the general circulation of the atmosphere and the summer precipitation data over North China.Results show that the Arctic oscillation had obviously inter-decadal variation and an abrupt change in 1969.The inter-decadal variation of Arctic oscillation was in good agreement with the inter-decadal variations of the mid-latitude potential height anomaly field and the 850hPa wind field over Asia.The Arctic oscillation was close related with the frequency of blocking high over the Baikal Lake area and the intensity of East Asian summer monsoon and summer precipitation over North China.