Abstract: In this paper,under the assumption of neutral and barotropic atmosphere,by means of the analytic solution of.motion equation PBL,the influences of nonstationary process on the inner parameters u*/A(A is the wind speed at the top of PBL) and φ (the angle between the wind near surface and the wind at the top of PBL) of PBL are investigated in which the direction of the wind at the top of PBL is a periodic function of time but the wind speed at the top of PBL is not changed.The u*/A increases and φ decreases when the wind direction at the top of PBL rotates anticlockwise,and vice versa.Hence the parameterizalion of PBL in the large scale models which was derived in the stationary conditions should be corrected by accounting for the nonstationary process.The similar results are obtained in the numerical solution of the motion equation of PBL.The influences of this nonstationary process on the profiles of wind in PBL are also analyzed.