Green's functions for extended displacement discontinuity in a three-dimensional two-phase transversely isotropic magnetoelectroelastic medium are obtained by using the integral equation method. Based on the obtained Green's functions, an extended displacement discontinuity method is developed for analysis of planar cracks of arbitrary shape in three-dimensional two-phase magnetoelectroelastic media. A rectangular interior crack parallel to the interface under the electrically and magnetically impermeable boundary condition is analyzed, and the extended intensity factors are calculated by the proposed method. The magnetoelectroelastic medium is made with BaTiO 3 as the inclusion and CoFe 2 O 4 as the matrix. The influences of the interface and the material properties on the extended intensity factors are studied. Numerical results show that the three normalized extended intensity factors, that is, the stress intensity factor, the electric displacement intensity factor, and the magnetic induction intensity factor, are different both from each other and from the case of a crack in a homogeneous medium.