Abstract: With the uninterrupted increasing of vehicle velocity, boundary layer near field noise has attracted much attentions recently. This paper researchs its mechanism and presents a theoritical calculation method. The results of the research show that boundary layer near field noise is related to the wall shear stress, Spectral curve of vertical fluctuating velocity and local Reynolds number. The numerical calculation results relating √P_W²/τ_W to R_e,x are basically Coincident with the experimental results by Corcos¹ and Hodgson⁹.