This work studies the impact of the vertical shear of gradient wind (VSGW) in the free atmosphere on the tropical cyclone boundary layer (TCBL). A new TCBL model is established, which relies on fi ve-force balance including the pressure gradient force, Coriolis force, centrifugal force, turbulent friction, and inertial deviation force. This model is then employed to idealize tropical cyclones (TCs) produced by DeMaria’s model, under diff erent VSGW conditions (non-VSGW, positive VSGW, negative VSGW, and VSGW increase/decrease along the radial direction). The results show that the free-atmosphere VSGW is particularly important to the intensity of TC. For negative VSGW, the total horizontal velocity in the TCBL is somewhat suppressed. However, with the maximum radial infl ow displaced upward and outward, the radial velocity notably intensifi es. Consequently, the convergence is enhanced throughout the TCBL, giving rise to a stronger vertical pumping at the TCBL top. In contrast, for positive VSGW, the radial infl ow is signifi cantly suppressed, even with divergent outfl ow in the middle-upper TCBL. For varying VSGW along the radial direction, the results indicate that the sign and value of VSGW is more important than its radial distribution, and the negative VSGW induces stronger convergence and Ekman pumping in the TCBL, which favors the formation and intensifi cation of TC.