In this paper,a method based on digital holographic tomography is pro posed to reconstruct the tomogram distribution of the refractive index of the single-mod e fibers (SMFs),for which only the phase distribution reconstructed from the digital hologram obtained in one rotation angle is needed,due to the axes symmetry of the refractive index in the single-mode fib ers.The three dimensional distribution of the refractive index of single-mode fibers can be o btained by each tomogram distribution of the refractive index.Compared with the previous approa ches for measuring the refractive index of single-mode fibers,this method is more non- destructive,simple and fas.The validity of the proposed method has been confirmed by both th e theory analysis and the optical experiment.