The physical weak-discontinuous problem of an interfacial crack between homogeneous materials and functionally graded materials (FGMs) is studied based on Reissner's plates considering transverse shear deformation effect. The higher order crack tip fields of homogeneous materials and FGMs regions are obtained by the eigen-expansion method. The normalized stress intensity factors(SIFs) and stress distributions near the crack tip are computed and compared by means of the higher order fields and singular fields, respectively.