Abstract: By use of geostrophic momentum approximation, the analytical expressions of the wind distribution within the planetary boundary layer and the vertical velocity at the ton of the boundary layer are obtained when the distribution of eddy transfer coeffiecent k devide into three sections as follows: k1z(z0≤zh1),k2(h1≤zh2),k3(h2≤z).The results are in agreement with the observations. In particular, the wind profile in the suface layer (z0≤zh1)coincides with the logarithmic distribution. The maximum of the angles between the wind near the surface ann the wind at the bottom of the free atmosphere only about 30°.This work improves Wu and Blumen's work1 which introduced the geostrophic momentum approximation to the boundary layer. The solutions in barotropic and neutral conditions have been also extended to the baroclinic and stratified atmosphere.