Based on the complex variable techniques and linear piezoelectric theory， we derive a semi-analytical solution for the plane problem of a periodic piezoelectric fibrous composite to explore the distribution of the local stress field and predict the effective stiffness of the composites. Specific series with unknown coefficients are introduced to describe the complex potential functions of the representative unit cell of the composites. The unknown coefficients are determined from the continuity conditions on the interface and the periodic boundary conditions imposed on the edge of the unit cell. Once the complex potential functions are determined， the effective stiffness and effective piezoelectric constant of the composites are obtained according to the average-field theory. The numerical results show that when the modulus of the matrix is larger than that of the piezoelectric inclusion， the influence of the electric loading on the local stress field around the inclusion is significant. The positive electric loading along the polarization direction of the piezoelectric inclusion may induce the orientation of the maximum equivalent stress on the interface of the matrix and the inclusion to change 90° relative to the case of non-electric loading or negative electric loading. On the contrary， the electric loading has little effect on the local stress field. Because of the symmetry of the microstructure， the composite shows the same stiffness along the two symmetrical axes. It is also found that the effective piezoelectric constant is sensitive to the modulus of the matrix.