In　this　paper,　the　influences　of　the　induced　Coulomb　tractions　on　the　static　and　dynamic　crack-tip　fracture　parameters　of　semi-permeable　piezoelectric　cracks　are　studied　and　discussed.　The　static　crack　problems　are　solved　by　a　static　dual　boundary　element　method　(BEM),　while　the　corresponding　crack　problems　under　dynamic　impact　loading　are　numerically　analyzed　by　a　time-domain　BEM　considering　the　inertial　effects.　In　the　numerical　implementation,　a　collocation　method　is　applied　for　the　spatial　discretization　together　with　a　quadrature　formula　for　the　temporal　discretization.　An　iterative　scheme　based　on　the　quasi-Newton　method　is　adopted　to　solve　the　corresponding　non-linear　boundary-value　problem　resulted　from　the　semi-permeable　electric　boundary　conditions　and　the　induced　Coulomb　tractions　on　the　crack-faces.　The　crack-tip　facture　parameters　involving　the　field　intensity　factors,　the　energy　release　rate　and　the　mechanical　strain　energy　release　rate　are　evaluated　by　a　displacement　extrapolation　method.　Some　examples　are　presented　to　compare　the　effects　of　the　Coulomb　tractions　on　the　static　and　dynamic　fracture　parameters.