Abstract: Two types of roughness element numbers and five thicknesses of element heights were used to investigate the influence of modal surface roughness on wind loads of cooling towers. The technique of proper orthogonal decomposition method (POD) was employed to interpolate and reconstruct the wind pressures on the towers. The distribution of wind pressures and overall wind forces on the cooling tower were analyzed with respect to surface roughness. Then the experimental results were compared with the data of the Code, previous full-time tests, and previous wind tunnel tests. The results from this study show that if the surface of the tower model is smoother, the absolute value of the wind pressure on layer B (near the throat) is larger. When the number of surface roughness elements increases, the base shear coefficients of the cooling tower become larger, resulting in larger overall wind-resistant forces. The drag coefficients near the throat of the cooling tower are close to the data of the Code, whereas the drag coefficients of the top and the mid-bottom of the tower are larger than the data of the Code, in which additional attention should be paid by the designers.