A spectroscopic optical coherence tomography (OCT) system based on the principle of spectroscopic OCT was built, and the reflectance spectrum of multilayer film was measured. This method uses the Fourier transform to pick out the spectral information of OCT signals, and overcomes such limitations of existent film reflectivity measurement methods as lack of intuitionstic results and non-metrical surface interference. The gained spectral reflectivity matches well with the result calibrated by commercial instrument, and the mean square error turns out to be only 0.0488.