This　paper　puts　forward　a　new　method　of　improving　the　electro-optic　crystal＇s　electric　field　distributions　by　attaching　some　kind　of　media　on　the　electro-optical　crystal.　Through　the　simulation　of　a　110　kV　OVT　(Optical　Voltage　Transducer)　the　method　is　proved　being　effective　in　improving　the　distributions　of　electric　field　in　crystal　and　reducing　the　measurement　errors　caused　by　an　optical　path　offset　and　interference　field.　The　improvement　can　ultimately　increase　the　accuracy　and　stability　of　the　OVT.