Light scattering losses from dielectric multilayer are becoming increasingly important for designing high precision performance optical devices. In this paper, we applied the bi-directional reflectance distribution function of optical multilayer and analyzed the total reflectance scattering losses based on both the completely correlated and non-correlated interface models to compare with a high reflection 17-layer optical multilayer deposited on roughness of 2.8 nm substrates. The experimental result supports the completely correlated interface model as firstly the wavelength dependence is in good agreement with the phase change of the calculated result and secondly the calculated scattering intensity of the completely correlated interface scattering model is approximately the same as that of the measured scattering spectrum, while the intensity using the non-correlated interface scattering model is significantly higher than the measured result in the high transmission ranges and lower in the main band of the high reflection range. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.