In　this　paper,　the　crack-tip　field　intensity　factors　of　a　piezoelectric　crack　are　respectively　evaluated　by　an　interaction　integral　(M-integral)　and　a　modified　crack　closure　integral　method　(MCCI).　By　applying　the　dual　BEM　to　piezoelectric　crack　models,　the　crack-tip　fracture　parameters　using　M-integral　and　MCCI　are　verified　by　the　existing　analytical　solutions　and　compared　with　the　results　by　the　classical　displacement　extrapolation　and　J-integral　methods.　Some　examples　are　presented　to　show　the　high　accuracy　of　M-integral　and　the　improvement　of　MCCI　for　the　piezoelectric　crack　problems.