The　single　wavelength　off-axis　reflection　digital　holographic　microscopy　(DHM)　can　be　applied　in　micron　optical　tomography　measurement　through　the　pre-magnification　method.　The　pre-magnifying　surface　profile　of　the　object　is　imaged　by　the　lens　placed　in　front　of　the　object　to　be　measured,　and　then　is　recorded　by　the　CCD　camera.　The　Reconstructed　image　can　be　got　through　Fresnel　Diffraction　calculation,　the　3D　surface　shape　information　of　the　object　was　shown　after　the　phase　filtering　and　unwrapping　process　to　the　reconstruction　image.　The　result　in　this　experiment　proves　that　off-axis　reflection　digital　holographic　microscopy　can　be　applied　to　actual　measurement　of　micron　object,　to　achieve　the　tomography　without　touching　or　breaking　the　object.