Application of dielectric functional gradient insulation（d-FGI）into insulation part can significantly homogenize the electric field distribution

and hence effectively improve its insulation performance. How to select the optimal dielectric parameters（conductivity/permittivity）distribution in the design of d-FGI insulation part is the key issue for the study in this field. In this paper

such three kinds of different types of algorithms as intelligent optimization algorithm for two-layer dielectric gradient optimization

iterative optimization algorithm for multi-layer dielectric gradient optimization and topology optimization algorithm for point-by-point dielectric gradient optimization are adopted respectively for optimization of different forms of dielectric parameter distribution truncated cone insulator model. It can be seen from the optimization result that these three kinds of optimization algorithms can reduce effectively the electric field strength near the"triple junction point"of electrode-insulation-gas atmosphere in the truncated cone insulator parallel plate electrode and expect to improve the electrical strength of the insulator. Furthermore

it is founded that in the three kinds of d-FGI design methods

the electric field optimization effect of point-to-point dielectric gradient topology optimization method is more remarkable and has more flexibility and advanced performance.