Abstract:With correlation and resultant analysis methods，the climate aspects between the tendencies of drought and flood in Beijing and the abnormities of 500hPa circul ations are analyzed, by using the data of 500hPa height fields, subtro pical high character fields and Beijing's precipitation. The results show that t he strength and the position of the subtropical ridge are not remarkably associa ted with the summer precipitation in Beijing, while the flow pattern collocation s between the mid high latitudes and the subtropics are. The drought summers of Beijing were associated with the tele connection pattern over Eurasian continen t mid high latitude (EUP pattern). In those years, anticyclone circulation preva ils in Northern China with ridge to the western side of Beijing. Beijing and near by regions are controlled by Northwest descending flow. On the other hand, a b lock high pressure in the down stream side of Beijing is the basic circulation c haracteristicsfor plentiful precipitation summers of Beijing. In those years, B eijing and near by regions are controlled by Southwest ascending flow in front o f trough. These results provide some knowledge on large scale circulation backgr ound for seasonal prediction of summer precipitation tendency in Beijing.