An in-depth investigation is made on the problem of an arc-shaped interface insulating crackin a three-phase concentric circular cylindrical piezoelectric composite constitutive model.An exact solutionin series form is derived by employing the complex variable method.In addition,the distribution of physicalquantities such as stresses,strains,electric displacements and electric fields in the whole field and along theinterface is also presented,Explicit expressions for crack opening displacement,jump in electric potential onthe crack surface and the electro-elastic field intensity factors at the crack tips are obtained.Specific calcula-tions demonstrate that the convergence of the series form solution is satisfactory and that the outer phase(composite phase) will exert a significant effect on the electro-mechanical coupling response of the compositesystem.Owing to the fact that stresses and electric displacements still possess conventional inverse square ro-ot singularities,the oscillating singularities near the crack tip under plane strain conditions will be absentand,as a result,no unphysical interpenetration phenomenon of the two crack surfaces will occur.In conclu-sion,the elastic solution obtained is also based on a solid physical foundation. An in-depth investigation is made on the problem of an arc-shaped interface insulating crack in a three-phase concentric circular cylindrical piezoelectric composite constitutive model. An exact solution in series form is derived by employing the complex variable method. In addition, the distribution of physicalquantities such as stresses, electrically, displacements and electric fields in the whole field and along the interface is also presented, Explicit expressions for crack opening displacement, jump in electric potential on the crack surface and the electro-elastic field intensity factors at the crack tips are obtained. Specific calcula-tions demonstrate that the convergence of the series form solution is satisfactory and that the outer phase (composite phase) will exert a significant effect on the electro-mechanical coupling response of the composites system. Owing to the fact that stresses and electric displacements still substantial conventional inverse square ro-ot singularities, the oscillati ng singularities near the crack tip under plane strain conditions will be absentand, as a result, no unphysical interpenetration phenomenon of the two crack surfaces will occur. In conclu-sion, the elastic solution is also based on a solid physical foundation.