This article studies the broadband noise of a rotor in upstream turbulence.A numerical approach is proposed,based on frequency domain,for predicting rotor broadband noise which requires the aerodynamic sources to be integrated over the actual blade surface rather than over the mean-chord surface.The prediction of the radiated rotor broadband noise due to turbulence is made.This method is validated through a comparison between numerical predictions and measured data,with a reasonable agreement.Noise level directivity shows that the main lobe is located along the rotor axis,while the minimum noise occurs in the direction vertical to the rotor axis.