An　explicit　extrapolating　formula　for　a　general　case　of　the　interfacial　crack　plane　lying　with　an　angle　to　the　poling　axis　in　transversely　isotropic　piezoelectric　(TIP)　materials　is　derived,　which　is　very　feasible　to　determine　the　intensity　factors　for　numerical　methods　such　as　FEM　or　BEM.　Additionally,　a　more　concise　extrapolating　formula　for　the　typical　state　of　the　interfacial　crack　plane　lying　perpendicular　to　the　poling　axis　is　also　presented　in　this　paper.