A coupled CFD/free-wake method is developed in this paper to predict the rotor blade-vortex interaction aerodynamics. In order to improve computational efficiency, an efficient coupling strategy is presented here to pass the flow variables between two domains. Based on this, the FW-H equation is adopted to predict the rotor blade-vortex interaction noise. By the method, the effects of atmospheric environment on blade-vortex interaction noise radiation characteristics of operational loads survey（OLS）rotor are analyzed. The results indicate that with the increase of flight height, an apparent variation of radiation characteristics happen, namely the noise hot spot shifts to the front part of rotor plane from the advancing side of rotor plan and the maximum sound pressure level(SPL) first increase and then decrease. In view of this phenomenon, the effects of atmosphere pressure, sound velocity and air density on rotor blade-vortex interaction noise radiation characteristics are deeply analyzed from the variation of miss-distance and interaction locations.