Three-dimensional（3D） electric field of 330 kV long-rod composite insulator is calculated by using ANSYS software

a finite element analysis（FEA） software package.The effects of conductor

tower configuration and grading devices on the electric field and voltage distribution along the insulator（I type） are discussed.ANSYS optimized method used to search the reasonable parameters（height

ring diameter and tube diameter） of grading ring.The result shows that the conductor line is the main factor for improving voltage distribution along the 330 kV long-rod composite insulator in service condition.Tower configuration has less effect.Grading ring near the end of insulator conductor can reduce the electric field strength at organic material（internal housing and core）.