DC filter components and devices in converter stations of a high voltage DC transmission project may withstand a certain amount of transient overvoltage due to the impact of transient impulses.In order to protect them,suitable arresters should be equipped properly in the filters to limit the transient overvoltage to an acceptable level.By utilizing the method of DC filter simulation and transient calculation model,the paper studies the transient overvoltage in the DC filters of the Jinping-Sunan ultra high voltage direct current(UHVDC) transmission project under the most severe transient operation conditions.Three arresters are installed inside each filter,which consequently decide the insulation levels of the filter component: mainly capacitors,reactors and resistors.The lightning impulse insulation levels for the high voltage reactors of the two filters are 648 kV and 788 kV respectively,while they are 464 kV and 627 kV for the low voltage reactors,and 648 kV and 788 kV for the resistors.The insulation level for the high voltage capacitors is no more than 815 kV.The calculation results provide basis for choice of the DC filter components. DC filter components and devices in converter stations of a high voltage DC transmission project may withstand a certain amount of transient overvoltage due to the impact of transient impulses. Order to protect them, suitable arresters should be equipped properly in the filters to limit the transient overvoltage to an acceptable level. BY the method of DC filter simulation and transient calculation model, the paper studies the transient overvoltage in the DC filters of the Jinping-Sunan ultra high voltage direct current (UHVDC) transmission project under the most severe transient operation conditions.Three arresters are installed inside each filter, which determines decide the insulation levels of the filter component: mainly capacitors, reactors and resistors. The lightning impulse insulation levels for the high voltage reactors of the two filters are 648 kV and 788 kV respectively, while they are 464 kV and 627 kV for the low voltage reactors, and 648 kV and 788 kV for the resistions tors. the insulation level for the high voltage capacitors is no more than 815 kV. The calculation results provide basis for choice of the DC filter components.