Based on a complex potential theory of linearpiezoelectric materials and series expansion of the complex potential, ageneral method is proposed for solving the crack problem of a finitepiezoelectric plate. By this method, fracture parameters such as the stressintensity factor, the electric displacement intensity factor and energyrelease rate et al. can be easily evaluated under the impermeable boundarycondition. Numerical results of fracture parameters demonstrate that theproposed method gives satisfactory results compared with the existingsolutions given by Woo and Wang for a central crack in a finitepiezoelectric plate. This method is identified to be an accurate andefficient method. An experiment with a PZT-4 compact tension specimen hasbeen modeled under the impermeable boundary condition by the present method,and the critical values of fracture parameters are greatly varied and notthe material constants. Therefore, these fracture parameters are not used asthe single-parameter fracture criterion for the piezoelectric material.Then, in terms of the PZT-4 compact tension specimen, the influence ofpermeability of the crack has been studied based on the results of finiteelement calculations. The finite element model of the PZT-4 compact tensionspecimen with an actual crack profile is analyzed for two different electricpermeability of the medium in the crack cavity corresponding to animpermeable medium and silicone oil. The largest applied negative electricfield and the corresponding mechanical load for fracture are considered.Finally, the crack profile in the PZT-4 compact tension specimen can beregarded to be composed of a notch and an ideal crack (so-called microcrack)in front of the notch. The model of this assumed crack profile has beenanalyzed by the finite element method.