In this paper we studied a finite crack in an infinite medium made of a functionally gradient piezoelectric material subjected to antiplane shear and inplane electric field. The material properties, including the elastic shear modulus, the piezoelectric modulus and the dielectric modulus are assumed to vary exponentially with spatial position. By means of Fourier transformation, the governing equations of the problem are firstly reduced to two pairs of dual integral equations and then to a Fredholin integral equation of second kind. The electroelastic fields are completely determined and the field intensity factors can be defined. It is found that the stress and the electric displacement have the inverse square-root singularity at the crack tip as that of homogeneous piezoelectric materials, and the stress intensity factor and the electric displacement intensity factor increase with the increase of the material gradient constant of functionally gradient piezoelectric materials.