This　paper　investigates　the　possibilities　of　optimizing　the　Pockels　electric　field　in　a　transverse　modulated　optical　voltage　sensor　with　a　spherical　electrode　structure.　The　simulations　show　that　due　to　the　edge　effect　and　the　electric　field　concentrations　and　distortions,　the　electric　field　distributions　in　the　crystal　are　non-uniform.　In　this　case,　a　tiny　variation　in　the　light　path　leads　to　an　integral　error　of　more　than　0.5%.　Moreover,　a　2D　model　cannot　effectively　represent　the　edge　effect,　so　a　3D　model　is　employed　to　optimize　the　electric　field　distributions.　Furthermore,　a　new　method　to　attach　a　quartz　crystal　to　the　electro-optic　crystal　along　the　electric　field　direction　is　proposed　to　improve　the　non-uniformity　of　the　electric　field.　The　integral　error　is　reduced　therefore　from　0.5%　to　0.015%　and　less.　The　proposed　method　is　simple,　practical　and　effective,　and　it　has　been　validated　by　numerical　simulations　and　experimental　tests.　©　2018　IOP　Publishing　Ltd.