Periodical oscillations of the horizontal transfer of the atmospheric heat through the "outside walls" of the Qinghai-Xizang Plateau during the Qinghai-Xizang Plateau Meteorological Experimentin the summer of 1979 are analyzed in detail by means of power spectrum. It is found that there are two major oscillation periods,i. e., quasi-two weeks (13.3 days) and quasi-one week (6.7 days). Some physical reasons are presented for the quasi-two-week period of the horizontal heat transfer.