The　roll　angle　measurement　is　difficult　to　be　achieved　directly　using　a　typical　commercial　interferometer　due　to　its　low　sensitivity　in　axial　direction,　where　the　axial　direction　is　orthogonal　to　the　plane　of　the　roll　angular　displacement.　A　roll　angle　measurement　method　combined　diffraction　gratings　with　a　laser　heterodyne　interferometer　is　discussed　in　this　paper.　The　diffraction　grating　placed　in　the　plane　of　a　roll　angular　displacement　and　the　interferometer　arranged　in　the　plane＇s　orthogonal　direction,　constitute　the　measurement　pattern　for　the　roll　angle　with　high　resolution.　The　roll　angular　displacement,　considered　as　the　linear,　can　be　tested　precisely　when　the　corresponding　angle　is　very　small.　Using　the　proposed　method,　the　angle　roll　measurement　obtains　the　high　resolution　of　0.002　＇＇.　Experiment　has　proved　its　feasibility　and　practicability.　(C)　2014　AIP　Publishing　LLC.