This work revisits the generalized 2D problem of electrically permeable collinear interface cracks in piezoelectric materials with two motivations: one is to present a more explicit approach to the considered problem; the other is to derive some new results for periodical interface crack problem in piezoelectric materials with the use of the new approach. Based on the Stroh formalism, the mechanical–electric coupling boundary equations are decoupled into two equations: the first one is related only to the applied mechanical loads, and the second one only to the applied electric field. According to the traditional method or available results, the solution for the first equation can be given, and then the solution for the second equation can be directly written out by using the results of the first equation. Furthermore, the solutions for infinite number of periodical collinear interface cracks are at the first time presented in closed form. The solutions include the field intensity factors and the electric fields both inside and outside the cracks. It is shown that under the electric loading only, the electric fields are uniform not only in the materials but also inside the cracks, while the stress is zero wherever. However, when the combined mechanical–electric loadings are applied at infinity, the electric fields inside the cracks may be singular and oscillatory, and such is the case for the stresses near the crack tips, but the intensities of all singularities depend on the material properties and the applied mechanical loads, not on the applied electric loads. Finally, a numerical example is given for the case of a single interface crack, and the electric fields inside the crack is shown analytically and graphically.