In order to accurately determine the refractive index of capsule, a method for measuring the refractive index of capsules is established based on the combination of white light vertical scanning interference (VSI) and white light reflectance spectra (WLRS). To solve the problems such as the difficulty to accurately determinate the peak positions and the possible interference order error in white reflectance spectra, the data processing method, in which the curve fitting is used to determine the peak positions and the interference order is determined by the continuity of interference order, is applied. The measurement, experimental verification and uncertainty analysis of the refractive index of glasscapsule are carried out. It is shown that the refractive index of capsule can be measured accurately by white light interference technique, and the measurement uncertainty is about 0.86%.