Abstract: By using IAP AGCM, it is proved that the anomaly in the antarctic iceis one of the import ant mechanisms to cause intraseasonal oscillation in the global at mosphere. The time-sequence of pontadly mean depature field is analized in this paper using the bandpassfil tering scheme. With special at tention to the charact eristics of 30-60 day oscillation in the response field, it was found that:The global at mosphere behaves long-time teleresponse to an anomalous external forcing from the ant arctic seaice, whose period ranges from thirty to sixty days. 30-60 day oscillation plays an importantrole in the forcing field, whose vertical structure and zonal propogation charact eristics in the model at mosphere is similar to that in real atmosphere. 30-60 day oscillation energy in response field increases with height. Longitudinal variation of the energy appears regional charact eristics. The maximum energy of intraseasonal oscillation emerges over the ocean because of CISK mechanism. The wavet rains of EUP, PNA, ASA and RSA, perhaps, are the main propogation routes of the low-frequency perturbation in the at mospheric circul ation. Consequently the 30-60 day oscillation in the region of middle-high and low lat itude or in the Northern and Southern Hemisphere keeps in contact with each other. It is suggested, that, the middle equatorial Pacific and Atlantic are the paths through which 30-60 day oscillations in the Northern and Southern Hemisphere interact.