Based on 1979-2007 seasonal NCEP/NCAR reanalysis data, relationships among Interhemispheric Oscillation (IHO), Arctic Oscillation (AO) and Antarctic Oscillation (AAO) are investigated.The results are shown as follows:1) Both AO and AAO have close relationship with mid-high latitude surfa ce pressure changes in their own hemispheres.AO in boreal winter emerge as strongest magnitude and influence broadly in both boreal spring and winter.AAO, on the other hand, exhibits most active in both austral summer and winter, and has notable impact on mid-high latitudes, especially in austral summer.2) IHO and AAO show significant positive correlation and AAO can partly explain the formation of IHO.IHO and AO exhibit insignificant negative correlations in all the four seasons.The relationships indicate that atmospheric circulation in mid-high latitudes in both the northern hemisphere (NH) and the southern hemisphere(SH) is relatively independent.3) IHO makes contributions to large scale surface pressure variation.With AAO signals removed, the significant area in SH polar region shrinks obviously.AAO has a close relation with IHO in summer.4) IHO bears a close relation to synchronous surface air temperature abnormally in Asia and north of Europe in boreal autumn, spring and winter.IHO has little relationship with surface temperature.It seems plausible that diabatic heating in northern European and Asian mainland can partly explain the formation of IHO.