Abstract: The length of triple suspension insulator string adopted in the UHV projects is always so long that it may result in the waste of engineering investment. In this article, so as to solve the problems mentioned above, the optimum design of the three-variable-two plane, triangle joint plate and hanging plate in suspension string was carried out based on the experience in design, manufacture, construction and operation of fittings used in ±800 kV UHVDC projects and 1 000 kV UHVAC projects. It is proposed that the three-variable-two plate in the three-wire clip suspension string should be placed on the low-voltage side and the original fittings at high voltage side should be replaced by the connection of the single-plate triangle plate and the double-plate triangle plate. Thought the careful simulation analysis of the mechanical characteristics and electrical characteristics of the proposed , as well as the real-model corona characteristic test research, the compact triple suspension string and matching fittings for the 1 000 kV projects were successfully designed. The total length of the insulator string can be reduced about 600 mm which can improve the economic benefit obviously.