A　segmental　dispersion　compensation　method　is　proposed　to　compensate　the　dispersion　in　frequncy　domian　optical　coherence　tomography.　Tomographic　imaging　for　epidermal　layer　of　an　onion　slice　is　achieved　in　the　experimental　setup　using　optical　fiber.　The　axial　resolution　of　the　tomography　can　be　improved　by　using　segmental　dispersion　compensation,　because　this　dispersion　compensation　method　employs　segmental　dispersion　coefficiens　for　the　different　lateral　positions　in　one　specific　layer.　Comparing　with　the　traditional　dispersion　compensation　method,　segmental　dispersion　compensation　method　has　the　capability　of　separating　the　specified　layer　of　sample　and　eliminating　the　dispersion　broadening　effect　of　specified　layer.