This　study　presents　a　novel　and　highly　accurate　method　of　measuring　the　geometric　thickness　of　the　self-lubricating　fabric　liner　of　bearings　by　combining　the　optical　coherence　tomography　(OCT)　technology　and　the　Hanning-windowed　energy　centrobaric　method　(HnWECM).　The　geometric　thickness　of　wear-resistant　coating　material　is　one　of　the　important　indicators　for　evaluating　its　wear,　and　the　measurement　of　its　geometric　thickness　is　of　great　significance　for　preventing　coating　failure.　To　address　the　issue　of　significant　measurement　errors　caused　by　using　the　refractive　index　of　the　sample　instead　of　the　group　refractive　index　to　calculate　the　material’s　geometrical　thickness　in　previous　OCT　research　and　applications,　our　proposed　method　can　accurately　measure　the　geometrical　thickness　of　materials　without　the　influence　of　the　refractive　index　of　the　material.　Moreover,　this　method　exhibits　the　advantages　of　non-contact　and　high　precision,　since　it　utilizes　an　SD-OCT　system,　making　it　a　novel　method　for　extracting　the　physical　parameters　of　composite　materials.　The　geometric　thickness　of　the　peeled-off　liner　obtained　from　our　method　is　compared　with　the　thickness　measured　by　the　spiral　micrometer　to　evaluate　its　accuracy.　The　experimental　results　indicate　that　the　thickness　measured　by　the　spiral　micrometer　was　172　μm,　while　the　maximum　difference　in　the　data　obtained　by　our　method　was　171.261　μm.　This　suggests　that　the　difference　between　the　two　methods　is　less　than　0.430%,　which　verifies　the　accuracy　and　validity　of　our　method.　Additionally,　the　obtained　geometric　thickness　and　the　optical　thickness　of　the　peeled-off　liner　are　used　to　evaluate　the　group　refractive　index　of　this　material.　The　inside　geometrical　structure　of　the　self-lubricating　fabric　liner　on　the　end　face　and　inner　ring　of　the　sliding　bearing　is　imaged　with　this　group　refractive　index.　The　measurement　of　the　inner　ring　liner　of　the　sliding　bearing　proves　the　flexibility　of　the　fiber-optic　OCT　and　provides　a　non-contact,　nondestructive　testing　method　for　measuring　the　geometric　thickness　and　internal　geometric　structure　of　composite　materials.　©　2023　by　the　authors.