Featured　Application　This　work　can　be　mainly　applied　in　the　optical　element　surface　quality　evaluation　field.　Abstract　Nanoscale　defects　on　the　surface　of　ultra-precision　optical　elements　seriously　affect　the　beam　quality　in　optical　systems.　In　response　to　the　challenge　of　detecting　nanoscale　defects　on　optical　component　surfaces,　we　propose　a　method　for　the　detection　and　classification　of　various　types　of　defects　on　optical　component　surfaces　via　reflection　Mueller　matrix　spectroscopy　(RMMS).　Firstly,　an　electromagnetic　scattering　theoretical　model　for　various　types　of　defects　on　the　surface　of　optical　elements　and　the　incident　and　scattered　fields　were　established　by　combining　the　bidirectional　reflection　distribution　function　(BRDF)　and　the　Rayleigh–Rice　vector　scattering　theory.　Then,　the　optimal　conditions　for　RMMS　measurements　were　determined　by　numerically　simulating　the　BRDF.　On　this　basis,　the　surface　roughness　and　pockmarks　of　the　optical　test　plate　were　simulated　and　analyzed　via　RMMS,　and　the　results　were　verified　experimentally;　then,　dirty　particles　and　pockmarks　above　the　surface　of　the　optical　element　and　subsurface　bubble　defects　(SSBD)　were　simulated　and　analyzed　via　RMMS.　The　results　showed　that　some　elements　of　the　Mueller　matrix　could　significantly　distinguish　defects　on　the　surface　of　the　optical　element　with　dimensions　smaller　than　the　visible　wavelength,　and　the　dimensions　of　various　types　of　defects　of　the　element　could　be　inverted　using　the　values　of　the　Mueller　matrix　elements.　This　method　provides　a　theoretical　basis　and　reference　for　the　detection　and　classification　of　various　types　of　defects　in　precision　optical　components.