An AC permanent magnet gain transformer device and its voltage regulation and control method. This device adds permanent magnet or permanent magnet assembly to the structure of traditional transformer, the magnetic pole surface of permanent magnet closely clings to laminated iron core, so that the intrinsic permanent magnetic potential of permanent magnet could be elicited under the excitation of the excitation current of primary winding, overlapped and compounded with excitation magnetic potential in the general magnetic loop of closed-loop laminated iron core, and so, it's able to induce the induction electromotive force formed after the superposition of excitation flux and permanent magnet flux at the output end of secondary winding. The method for voltage regulation and control of this invention is to: input a certain amplitude of pulse current to the primary winding in order to guarantee the generation of compound excitation effect, and change the pulse count of pulse current per unit time in order to change and adjust the input and output power of this AC permanent magnet gain transformer device. This AC permanent magnet gain transformer device and its voltage regulation and control method further enhance the power transfer efficiency of transformer device, thus make up the intrinsic spoilage of traditional winding coil and laminated iron core, and save energy.