As　the　optical　voltage　transformer　(OVT)　based　on　linear　electro-optic　effect　often　uses　the　transverse　modulation　mode,　the　uniformity　of　the　distribution　of　electric　field　in　the　crystals　directly　affects　OVT＇s　accuracy　and　stability.　Experimental　results　show　that　when　the　angle　and　the　position　of　the　incident　light　offset,　the　inhomogeneity　of　the　electric　field　causes　integral　voltage　error　in　the　optical　path.　In　order　to　resolve　this　problem,　a　new　method　of　attaching　the　medium　to　electro-optical　crystal　is　put　forward.　And　an　OVT　on　110　kV　voltage　grade　is　designed　based　on　this　method,　in　which　the　internal　electric　field　for　BGO　crystals　of　additional　medium　is　simulated　and　calculated　with　the　finite　element　software　Ansoft　Maxwell.　The　results　show　that　the　method　can　improve　the　uniformity　of　the　electric　field.　With　an　increase　in　the　thickness　of　glass,　the　uniformity　of　electric　field　is　improved　and　tends　to　be　stable.　To　attach　the　medium　to　the　electro-optic　crystal　when　the　light　path　has　an　offset　of　0.5°,　the　error　can　be　improved　from　0.11%　to　0.04%,　and　for　the　offset　of　0.1　mm,　the　error　can　be　reduced　from　0.3%　to　0.08%,　an　appreciable　improvement　on　the　electro-optic　crystal　edges　aggregation　effect.　©　2016　Automation　of　Electric　Power　Systems　Press.