Based on the general solution of piezoelectric media and the extended Cerruti solution for tangential point forces acted on the surface of transversely isotropic piezoelectric half-space (Ding and Chen, 2001), the electro-elastic fields in a transversely isotropic piezoelectric half-space caused by a circular flat bonded punch under torsion loading, which is called Reissner-Sagoci problem, are evaluated by first evaluating the displacement functions within the contact region and then differentiating them. All the coupling electro-elastic fields are expressed by elementary functions and are convenient to be used. Numerical results are finally presented.