Molecular　dynamics　simulations　of　body-centered　cubic　(bcc)　iron　thin　films　with　crack　defects　were　carried　out　by　adopting　methods　of　EAM　(Embedded　Atom　Method)　potential,　spin/exchange　potential　and　spin/neel　potential.　In　this　article,　the　effects　of　the　variation　of　distance　between　two　crack　defects　and　their　directions　on　the　magnetostrictive　properties　of　the　thin　films　are　studied,　and　the　corresponding　microscopic　mechanism　is　also　analyzed.　The　results　show　that　the　defects　affect　the　atomic　magnetic　moment　nearby,　and　the　magnetostrictive　properties　of　thin　iron　films　vary　with　the　direction　and　spacing　of　the　crack　defects.　If　the　defect　spacing　is　constant,　the　iron　model　with　crack　perpendicular　to　the　magnetization　direction　has　stronger　magnetostriction　than　that　of　parallel　to　the　magnetization　direction.　The　variation　of　the　defect　spacing　has　a　great　influence　on　the　magnetostrictive　properties　of　the　iron　model　with　crack　direction　parallel　to　magnetization　direction,　but　it　has　a　small　effect　on　another　perpendicular　situation.　The　atoms　between　the　defects　may　move,　but　if　the　defect　spacing　increases　to　a　certain　value,　then　none　of　the　atoms　will　move.