We　study　the　multi-transverse　mode　distributions　and　the　wavelength　splittings　with　different　designed　oxide　apertures　of　the　oxide-confined　VCSEL.　By　developing　the　effective　index　model　and　BPM　algorithm　theory,　the　characteristics　of　transverse　optical　field　distribution　are　calculated　with　circular　aperture　and　ellipsoid　aperture,　which　are　compared　with　our　experimental　results　of　multi-wavelength　spectra　of　high-order　transverse　modes.　The　results　show　that　the　orthogonality　of　the　different　crystal　orientation　modes　will　be　broken　by　the　oxidation-induced　ellipsoid　aperture,　and　the　maximum　wavelength　spltting　of　the　degenerated　high-order　mode　is　0.037　nm,　which　can　be　reduced　as　the　diameter　of　aperture　increases.　The　results　in　this　paper　will　provide　a　useful　reference　for　multi-transverse　mode　locking　of　oxide-confined　VCSELs.