Abstract: In this paper,the influence of atmospheric barolinicity on the dynamics of boundary layer with the Ekman momentum approximation is studied.Some new results are obstained.The atmospheric baroclinicity plays an important role in altering the horizontal velocity of the Ekman layer and the angele between the latitude component of velocity and the longtitude one near the surface.There are three different physical factors affecting the nonlinear Ekman pumping (the vertical motion) at the top of baroclinic boundary layer:First,the barotropic geostrophic near the surface; Second,the thermal wind vorticity due to the atmospheric baroclinicity; Third,the nonlinear effect of joint of barotropic geostrophic vorticity and baroclinic thermal wind vorticity.These results may provide a better physical basis for parameterization of boundary layer and the interpretation of the numerical moding results.