Radiation　loss　of　leaky　mode　in　anti-resonant　reflection　optical　waveguide　VCSELS　with　different　aperture　size　is　studied　by　cylindrical　anti-resonant　reflective　optical　waveguide　model.　The　result　indicate　that　radiation　loss　of　leaky　mode　in　anti-resonant　reflection　optical　waveguide　decreases　with　the　aperture　size　increases,　and　the　loss　margin　decrease　which　resulting　in　weakened　mode　discrimination　with　the　aperture　size　increases.　The　results　provide　an　important　reference　for　the　design　of　anti-resonant　reflection　optical　waveguide　vertical　cavity　surface　emitting　laser.　©　2012　OSA.