Based　on　the　linearized　magnetoelastic　theory,　analytical　solution　of　the　perturbed　magnetic　field　in　an　infinite　plate　by　a　circular　hole　under　extension　and　an　external　magnetic　field　was　obtained　in　this　paper.　The　results　show　that　the　perturbed　magnetic　field　induced　by　mechanical　deformations　is　3　orders　in　magnitude　smaller　than　the　magnetic　field　without　mechanical　deformations　4　peaks　and　vales　present　for　the　perturbed　magnetic　field　along　the　hole　boundary,　while　only　2　peaks　and　vales　present　for　a　deformation-free　magnetic　field.　It＇s　also　found　that　the　intensity　of　the　perturbed　magnetic　field　decays　very　rapidly　in　the　radius　direction　of　the　hole.