The invention relates to an overvoltage protection device for a variable impedance transformer. The overvoltage protection device is characterized by comprising a resistance-capacitance absorption device connected with a selector switch (K) and an air reactor in parallel, wherein the resistance-capacitance absorption device comprises a resistor R and a capacitor C1 connected in series, and arresters (MOV) are connected with two ends of the capacitor (C1) in parallel. When in use, the air reactor is placed in the box of a transformer, and a high-speed switch is positioned on the outer side of an oil tank and connected between the high-voltage winding and the neutral point of the transformer in series. When the variable impedance transformer works normally, the high-speed switch is closed, a current-limiting reactor is short-circuited, and the reactor is prevented from causing energy loss; when the system is short-circuited, the high-speed switch is open, the current-limiting reactor is available, then the transformer is equal to a high impedance transformer at the moment, and the short circuit current is inhibited to a certain extent. The device provided by the invention is compact in structure and small in size, and can effectively reduce overvoltage amplitude and gradient caused during an impedance conversion process of the variable impedance transformer.