Defects　are　an　inevitable　occurrence　during　the　manufacturing　and　use　of　ferromagnetic　materials,　making　it　crucial　to　study　the　microscopic　mechanism　of　magnetostrictive　properties　of　ferromagnetic　materials　with　defects.　This　paper　conducts　molecular　dynamics　simulations　on　low-dimensional　iron　thin　films　containing　hole　or　crack　defects,　analyzes　and　compares　the　impact　of　defect　size　on　magnetostrictive　properties,　and　investigates　the　microscopic　mechanism　of　their　effects.　The　results　indicate　that　the　saturation　magnetostrictive　strains　of　the　defect　models　do　not　increase　monotonically　as　the　defect　size　increases.　Additionally,　it　is　discovered　that　the　arrangement　of　atomic　magnetic　moments　in　the　initial　magnetic　moment　configuration　also　affects　the　magnetostrictive　properties.　When　controlling　the　size　of　the　hole　or　crack　within　a　certain　defect　area,　it　is　found　that　the　hole　size　has　less　influence　on　the　initial　magnetic　moment　configuration,　resulting　in　a　smaller　corresponding　change　in　the　saturation　strain　and　thus　having　a　lesser　impact　on　the　magnetostrictive　properties.　Conversely,　when　the　crack　size　changes,　the　arrangement　of　the　atomic　magnetic　moments　in　the　initial　magnetic　moment　configuration　changes　more　significantly,　resulting　in　a　greater　corresponding　change　in　saturation　strain,　and　thus　having　a　greater　impact　on　the　magnetostriction　performance.