The inhomogeneous refractive index distribution of scattering medium is measured by combining computed tomography (CT) with optical coherence tomography (OCT). The refractive index distribution is reconstructed by CT technique and the needed projections in different directions are obtained by OCT system. This method gets advantages over traditional optical refractive index measurement method, focus tracking method simply based on OCT and optical path matching method which cannot measure inhomogeneous refractive index distribution of scattering medium. The refractive index distribution of a gradient refractive index bar is measured and a favorable result is obtained.