The invention provides an overvoltage protection device suitable for a flexible looped network controller. The overvoltage protection device includes a first voltage limitator, a current interrupter and a voltage measurement device. The first voltage limitator is connected between a first AC terminal and a second AC terminal of the flexible looped network controller. The voltage measurement deviceis used for measuring a working frequency voltage component amplitude between the first AC terminal and the second AC terminal. The current interrupter is connected with the first voltage limitator in parallel and is used for interrupting rated AC current between the first AC terminal and the second AC terminal. Compared with the prior art, effective suppression on operation overvoltage, lightning overvoltage and working frequency overvoltage across two ends of the flexible looped network can be achieved and the operation reliability and safety are improved.