Abstract: Combined with the coherence function of fluctuating wind load, the average wind speed profile index and the mode index, the method of numerical integration was used to calculate the generalized aerodynamic spectrum of nonlinear modes for high-rise buildings in the downwind. The fitting formula for that value was derived by multivariate linear regression analysis, whose reliability was confirmed by the wind tunnel test. At the same time, the effect of nonlinear vibration modes on the generalized aerodynamic spectrum of high-rise buildings was discussed with the vibration index as the parameters:When the vibration mode index is less than 1, the correction coefficient is more than 1, that is, the calculated generalized aerodynamic force spectrum by the traditional method is too small, which is not safe for the structural design, and on the contrary, it is less than 1. Base on the generalized aerodynamic spectrum of the linear mode, it is recommended to use a correction factor of 1.1 in the basic mode of the load code for the design of building structures.