The　major　problem　in　the　fabrication　of　electronic　devices　on　plastic　substrate　arises　from　the　mismatch　and　weak　physical　bonding　between　inorganic　semiconductor　crystal　and　the　organic　plastics,　so　the　electrical　performance　stability　under　mechanical　stress　is　an　essential　factor　affecting　the　practical　application　of　flexible　electronic　sensors.　In　this　paper,　a　flexible　ZnO　nanowire　(NW)　UV　sensor　is　presented　as　an　exemplary　verification　for　investigating　the　effects　of　substrate　morphology　on　reliability　of　flexible　electronic　devices.　Sensors　on　ordinary　smooth　polyimide　(PI)　substrate　have　cracked　during　the　device　fabrication　process　due　to　the　residual　stress　caused　by　temperature,　humidity,　etc.　These　cracks　were　short　pieces　and　randomly　distributed,　so　they　may　not　significantly　affect　the　device　performance,　but　after　mechanical　bending,　cracks　that　penetrating　the　electrodes　were　generated　and　caused　electric　contact　failure.　Although　improving　the　ZnO　seed　layer　quality　could　reduce　the　cracking　and　buckling　that　formed　during　device　fabrication,　it　would　not　prevent　cracking　during　mechanical　bending.　In　a　3　x　3　sensor　array,　only　one　sensor　survived　after　bending.　Device　failed　when　the　bending　angle　larger　than　-　40　degrees　or　60　degrees.　On　the　contrary,　device　fabricated　on　textured　PI　substrates　exhibited　much　better　electrical　stability.　All　the　sensors　remained　their　original　performances　after　mechanical　bending　in　a　3　x　3　sensor　array.　The　light-dark　current　ratios　kept　in　the　level　of　10　5　under　the　365　nm　UV　light　of　15　mW/cm(2).　The　bending　angle　varied　from　-　80　degrees　to　80　degrees.　The　enhancement　of　electrical　stability　was　because　that　textured　substrate　could　tolerate　more　stress　than　smooth　substrate　to　prevent　the　film　from　cracking　and　at　the　same　time　it　could　increase　the　contact　area　between　ZnO　film　and　PI　substrate,　which　improved　the　interfacial　bonding　strength　and　delayed　the　local　strain　of　the　film.