The invention relates to a method for preparing giant field induced strain barium titanate single crystal. Positions of tetravalent titanium ions in crystal lattices are replaced by using doped trivalent ions, and the positions and oxygen vacancies in the crystal form a defective dipole moment. A barium titanate single crystal sample is prepared according to the length, width and thickness along the [100], [010] and [001] directions respectively; and electrodes are prepared on the surfaces of the sample in the width and thickness directions. A transverse electric field slightly higher than a coercive field is applied to the lateral electrode of the sample, the temperature of the sample is raised to a certain temperature below Curie temperature, and the sample is aged for over 1 day. In the ageing process, the spontaneous polarization direction of a domain in the sample is turned to an ageing electric field direction to form a single domain structure; and meanwhile, the defective dipole moment in the single crystal accelerates the diffusion motion under temperature rise, and under the action of the ageing electric field, the electric polarization direction of the defective dipole moment is gradually kept in accordance with the direction of the ageing electric field.