Abstract: In consideration of characteristics of low latitude area, such as high surface te perature,large amount of precipitation and evaporation, strong convergence and vertical motion, etc, a set of barotropic equations is presented.An important factor, sea surface temperature (SST), which influences remarkably the atmospheric waves in low latitude, is revealed.It is shown that: (a) when SST<25°C, the Rossby waves with evaporation-wind feedback propagate westward, when SST>25°C, the Rossby waves with evaporation-wind feedback propagate eastward, (b) the warmer the SST, and the wetter the air, the slower the speed of the Rossby waves with evaporation-wind feedback will be; the intraseasonal oscillations with the period of 30-40 day occur for SST>29°C.