The influence of curved surface on the method of polychromatic speckle measuring surface roughness is studied by introducing, surface curvature radius. The rough surface and the polychromatic speckle patterns near rough surface are simulated, and the influence of different curvature radii of rough surface on the simulated speckle patterns and ratio of speckle elongation is discussed. The results show that the factor of curvature radius of rough surface is valid in trichromatic speckle autocorrelation measurement, and the simulated speckle patterns and speckle elongation of rough surface are more similar to those of the straight surface when the curvature radius of the rough surface is larger. The larger the curvature radius is, the larger the speckle elongation becomes, and the smaller the deviation of measured surface roughness is. Therefore, influence of curvature of rough surface on measurement precision should be considered during the measuring process.