The utility model relates to a polycrystalline variable-current transformer comprising a primary winding (1), secondary windings (2) and an iron core. The primary winding (1) is connected in a triangular shape; the secondary windings (2) are three windings insulated from each other; the secondary windings (2) comprise auxiliary windings (3) for supplying control power supply; and the primary winding (1) is provided with shunting taps. Because of being provided with a control power supply, the polycrystalline variable-current transformer has wide voltage regulating range and can precisely detect and regulate the change ranges of voltage and current.