The electric field distribution characteristics of self-developed ±500 kV VSC-HVDC converter is calculated with the finite element analysis method for electrostatic field in this paper.The internal insulation characteristics of valve is investigated based on the maximum protection voltage of sub-module

and the outer insulation char acteristics of valve is investigated based on the lightning impulse test of supporting structure.Calculation results show that the maximum electric field value of the self-developed ±500 kV converter tower is 1.017 kV/mm in the air gap of valve components

1.619 kV/mm in the shielding system

2.941 kV/mm around the supporting insulator.So if 3 kV/mm is taken as the critical field intensity for corona inception of air

there will be no corona occurred on supporting struc ture during the lightning impulse test.Testing results show that the valve passes through experimental testing successfully without flashover

breakdown or discharge phenomenon with the current design

and there is no damage to the cooling system.The conclusion provides a reference for the insulation design of ±500 kV VSC-HVDC converter valve.