Abstract: In order to measure high reflectance and high transmittance of optic components and coat films, a precise measurement facility was set up which was based on single reflection measurement using laser power-stabilized technique, double optical path measurement technique and precise detection technique. High reflectance and high transmittance were measured at 632.8 nm and 1 064 nm wavelengths on the facility. Experiment result and uncertainty analysis showed that the measurement uncertainty of high reflectance and high transmittance was less than 0.008% at 632.8 nm and was less than 0.015% at 1 064 nm.