Under the stormy weather, rainfall directly changes the aerodynamic force of the structural surface and further affects the turbulence action of wind, but current wind resistance designs for cooling towers all ignore the additive effects of rainfall. To explore the effects of wind-rain on mechanical properties of cooling tower structures, a domestic large cooling tower which is the world’s tallest (210 m) was taken as an example, and based on wind-rain bidirectional coupling algorithm, the flow fields of cooling tower under three typical wind speeds were simulated based on computational fluid dynamics (CFD) technology. The discrete phase model (DPM) were added and the iterative computations of rain-wind coupling of 9 different combinations of wind speed-rain intensity were carried out. On this basis, the influence laws of different combinations of wind speed-rain intensity on rain drops moving trajectory and rainfall on tower drum surface were studied. Then the fitting formulas of equivalent pressure coefficients were proposed. The coupling models of the large cooling tower under different working conditions were established by the finite element method, and the structural responses of tower drum, pillars, and ring foundation under different wind speed-rain intensity combinations were compared. The research provides references for load forecast of such large cooling towers under extreme climates and complex working conditions.