Abstract: Using Ndrius-7 sateilite grid temperature data, the mean wind and gcopotential disturbution are caiculated and E-P flux are analysed in stratosphere and mesosphere.The results show that the stationary part of the quasi-stationary plancetary waves in middle atmosphere may not propagate across the zero wind line. The transient planeary waves are stimulated due to the amplitude fluctuation and phase variation of the quasi stationary planetary waves. They are not confined by the an wind line and can propagate across the Nuator from winter-hemisphere to summer-hemisphere or from summer-hemisphere to winter-hemisphere. The cross-equator propagation provide an explanation for the energy source of the planetary waves in summer hemisphere.