Electro-optic　integrated　electric　field　sensors　based　on　the　Pockels　effect　are　widely　used.　This　study　analyzed　the　measurement　error　caused　by　the　laser　wavelength　shift　and　the　underlying　theory　that　explains　it.　Numerical　methods　were　used　to　obtain　the　distribution　of　the　modulated　electric　field,　the　fundamental　mode　optical　field　and　the　refractive　index　of　the　LiNbO3(LN)　crystal　after　titanium　was　diffused　in　the　cross　section.　The　results　show　that　the　increase　of　the　wavelength　keeps　the　maximum　intensity　of　the　optical　field　centre　away　from　the　waveguide　surface,　moving　it　to　the　low　electric　field　intensity　region　and　reducing　the　electro-optical　overlap　integral　factor.　The　relationship　between　the　relative　error　of　the　measured　electric　field　and　the　wavelength　shift　was　finally　determined　through　calculation.　©　2022　IEEE.