Optical　reflection　anisotropy　microscopy　mappings　of　micropipe　defects　on　the　surface　of　a　4H-SiC　single　crystal　are　studied　by　the　scanning　anisotropy　microscopy　(SAM)　system.　The　reflection　anisotropy　(RA)　image　with　a　＇butterfly　pattern＇　is　obtained　around　the　micropipes　by　SAM.　The　RA　image　of　the　edge　dislocations　is　theoretically　simulated　based　on　dislocation　theory　and　the　photoelastic　principle.　By　comparing　with　the　Raman　spectrum,　it　is　verified　that　the　micropipes　consist　of　edge　dislocations.　The　different　patterns　of　the　RA　images　are　due　to　the　different　orientations　of　the　Burgers　vectors.　Besides,　the　strain　distribution　of　the　micropipes　is　also　deduced.　One　can　identify　the　dislocation　type,　the　direction　of　the　Burgers　vector　and　the　optical　anisotropy　from　the　RA　image　by　using　SAM.　Therefore,　SAM　is　an　ideal　tool　to　measure　the　optical　anisotropy　induced　by　the　strain　field　around　a　defect.