The　deformation　and　breakup　behaviors　of　droplets　containing　polymer　are　investigated　by　high-speed　photography　to　reveal　the　mechanism　of　electric　field　collapse　when　treating　the　emulsion　containing　polymer.　The　results　show　the　electric　field　collapse　process　caused　by　droplet　breakup　consists　of　three　steps.　First,　the　droplet　containing　polymer　ejects　liquid　filament　under　strong　electric　field.　Second,　the　liquid　filament　is　continuously　stretched　until　it　touches　positive　and　negative　electrodes.　Finally,　the　severe　Joule　heating　effect　appears　because　the　strong　electric　current　flows　through　the　liquid　filament.　The　release　of　a　large　amount　of　heat　causes　the　formation,　expansion,　and　collapse　of　bubble,　resulting　in　the　fracture　of　liquid　filament　and　the　collapse　of　electric　field.　The　increase　of　polymer　concentration　strengthens　the　Joule　heating　effect　and　enlarges　the　influence　scope　of　bubble　expansion　and　collapse.　These　findings　provide　significant　guidance　for　the　stable　operation　of　electric　dehydrator.