Abstract: Based on the data of April to June of 1981, the energetic processes of 14-day and 40-day oscillations were examined respectively. Eddy kinetic energy for both oscillations is generated mainly by meridional convergence of wave energy flux and conversion from eddy available potential energy, while the eddy available potential energy is generated by heating of condensation, suggesting possible excitation of the oscillations by lateral forcing due to midlatitude disturbances and sho-wing the importance of CISK in the maintenance of oscillation’s. The estimates show that the barotropic and baroclinic instabilities are less important, but the quasibiweekly oscillation can provide energy for the mean zonal flow in the upper troposphere of east Asia to maintain the upper level jet stream. On the other hand, a large amount or vertical wave energy flux from troposphere to stratosphere may be related to the existence of the 40-day oscillation.