The　change　of　electrical　properties　of　flexible　low-temperature　polysilicon　(LTPS)　thin-film　transistors　(TFTs)　under　biaxial　bending　strains　was　studied.　Biaxial　strains　were　applied　using　a　ring-on-ring　bending　test　rig.　The　magnitude　of　the　strain　was　determined　by　theoretical　calculations　and　finite-element　simulations.　With　an　increase　in　strain,　the　transfer　curve　shifted　to　a　negative　bias.　At　a　biaxial　strain　level　of　12%,　the　threshold　voltage　decreased　by　27%,　the　field-effect　mobility　decreased　by　13%,　and　the　subthreshold　slope　increased　by　25%.　It　had　a　more　significant　effect　on　the　property　changes　than　the　uniaxial　strain;　this　difference　may　be　attributed　to　additional　trap　states　generated　by　the　biaxial　strain.　The　analysis　showed　that　the　trap　density　increased　when　the　strain　level　increased.　The　contributions　of　the　increases　in　the　grain-boundary　trap　state　density　and　the　interface　trap　state　density　to　the　degradation　in　the　electrical　properties　were　derived　to　be　10%　and　90%,　respectively.　After　removal　of　the　biaxial　bending　strains,　the　electrical　performance　showed　recovery　behavior,　but　the　performance　could　not　return　fully　to　its　original　state.