Abstract: It is the purpose of this paper to investigate the effect of large-scale heating on the excitation of unstable disturbances. It is found that influence of heating on the barotropic unstable disturbances depends on the disposition of the heating and the flow field; in the westerly current the stationary wave patterm disturbances may be excited by heating and in the easterly current decaying disturbances may be excited only; the horizontal scale of diabetic heating which excite wave pattern disturbances must be R≥(u/β)1/2.At last, the effect of friction on disturbances is studied.