Abstract: The interference of the turbulence induced by valley terrain on the helicopter rotor has a profound impact on aerodynamic characteristics and flight safety. CFD simulations based on the standard k-ω turbulence model are conducted for the pressure-driven atmospheric boundary layer over a plateau valley model with appropriate inlet conditions. The flow fields are coupled with the hovering rotor using the overset mesh method to study the aerodynamic interference. Significant acceleration and deceleration phenomena are observed in the valley, and the turbulent kinetic energy diminishes gradually with increasing altitude. Typical turbulence characteristics, such as downwind motions, vorticities, and downdraft, are prevalent in the valley. The upward velocity component of the downwind flow between the valleys enhances the rotor’s thrust coefficient and hovering efficiency, albeit at the expense of increasing its pitch moment and inducing oscillation. The airflow in the vortex area is disordered, with the flow direction constantly changing. Moreover, the aerodynamic force of hovering rotors at similar positions changes considerably, potentially leading to the wind shear phenomenon. Downdraft can reduce the rotor’s thrust coefficient and hovering efficiency, and the region with high turbulent kinetic energy in the downdraft can easily cause the pitch moment oscillation of the rotor. The research results can provide technical support for helicopter flight strategy and flight safety control in complex terrain environment.