Abstract: The paper analyzed accidents in application of combined overvoltage protector in a substation in Yangquan mining area of Shanxi province and a pumped storage power station in Hubei province. It introduced principle and working characteristics of combined overvoltage protector, discussed problems of combined overvoltage protector, and pointed out that the structure of upper and lower ZnO elements of combined overvoltage protector could lead combined overvoltage protector no action at acting moment and accidents because of its own damage when lightning overvoltage happens. It also proposed points for attention in application of combined overvoltage protector, namely combined overvoltage protector cannot take the place of important lightning protection device and be used for lightning protection for important device.