Integral scattering is one of the important loss components of high-reflection optical thin films, so suppressing integral scattering can enhance the reflectance of high-reflection coating. Using integrating sphere is the important method of the integral scattering measurement of high reflection coatings. The paper introduced the measurement method and apparatus of integral scattering for single-wavelength at incident angle of 45deg by analyzing the principle of integrating sphere. Besides the important error sources and measurement accuracy of the integral scattering were analyzed. High-reflection coating for single wavelength onto fused silica substrate at incident angle of 45deg was manufactured by ion beam sputtering deposition and integral scattering apparatus was used to measure integral scattering of high-reflection coating. Finally by comparison of the experimental result and the value of scattering theory, we achieved the practical measurement errors origin that and established the foundation of scattering loss analysis for the ultra low losses high-reflection coating.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.